Mark's Dive Log

I've started to look into technical diving. I have a lot more training to do before I can start thinking about it seriously, but I've been thinking about it nonetheless.

I'm looking into what I need to do to prep myself for technical diving training. I've already picked up a Nitrox certification, which most seem to consider to be the starting point. I'm also working on the Rescue Diver certification, mainly because it's a prerequisite for Master and Divemaster.

The other specialties I'm going to try to pick up in the next year that I think would benefit me in my goal are Deep Diver, Multilevel Diver, Dry Suit Diver, Night Diver, and Wreck Diver. My reasoning:

Deep Diver: Seems kind of obvious, since technical diving generally involves going deeper, or longer, or both. So this one is on the short list.

Multilevel Diver: I'm presuming that this will be more than just learning how to operate the PADI Wheel. It would seem that it would be about learning more about diving physiology which would add to the base knowledge needed for technical diving.

Dry Suit Diver: Technical diving generally involves exposure to colder water or longer exposure times. Using a dry suit is fairly standard.

Night Diver: Since one part technical diving is diving in limited visibility environments (caves, wreck penetration, or just plain really deep water), the skills learned in the night diving course would seem to be useful.

Wreck Diver: The main reason I'm interested in technical diving is for exploring wrecks. Wreck Diver is a prerequisite to the technical wreck diver certification offered by some certification agencies. Even it it wasn't, I want to do wreck diving, so this one is on the short list (i.e. next year).

I have several other specialties on my short list, like Underwater Photographer and Search and Recovery, but these are just 'cause I want to do them.

There are a lot of diving activities that fall into the technical diving scope from cave diving to underwater filmography. Most uninformed people think of "technical diving" as the "lunatic fringe" of diving. While I agree that the lunatic fringe are part of the technical diving community, most technical divers are completely uninterested in cheating death. They are quite interested in staying alive. I fall in that category. I'm not interested in pushing the limits of known diving. I want to live in the parameters determined by others.

Interestingly, many of the activities I participate in are things that the uninformed consider risky or dangerous: flying, scuba diving, motorcycle riding, hunting, etc. I do enjoy activities that are more dangerous than watching TV or playing shuffle board, but they are hardly life threatening activities. It's about risk management: you learn what the risks are and learn how to mitigate them.

From a diving perspective, especially technical diving, that means learning everything you can about the hows and the whys so you can develop safe dive plans and handle any emergencies that come up maximizing your chance of survival. If you understand the things that can go wrong and make contingency plans for those problems, the risk of death or serious injury becomes almost negligible.

Obviously you can't completely eliminate the risk, but then again, you could slip in the bathroom, hitting your head on the sink, and bleed to death before someone finds you unconscious on the floor. Do you have a contingency plan for that? Don't take a shower without a buddy! Some risks are so small as to be not worth worrying about. With proper planning and risk management, so called "dangerous pastimes" are like that. Most people get hurt (or killed) in these activities are the victims of poor planning or risk management.

So to those who look at technical diving as some kind of crazy stunt like base jumping off a downtown building, just remember that you don't take a potty buddy with you to the bathroom, so you must be just as crazy as me.

As I mentioned earlier, I've been looking into technical dive training. After a lot of research, questioning a lot of people, and doubling my logged dive count I have enrolled in a Transition to Tech course that was designed by C. Stephen "Doc" Oborn to develop the diving skills of those interested in tech diving prior to starting the DSAT TecRec course. The idea is that if he can start training you to dive like a technical diver before you actually start the technical dive training, then the tech training will be that much easier. So instead of waiting until you have the 100 dives to start thinking and diving like a technical diver, you start before you've developed too many bad habits and then reinforce the tech thinking while getting the 100 dives.

Not only does this provide transition path from recreational style to technical style diving, it also makes it easier because you are learning some of the tech stuff earlier and reinforcing it with practice rather than practicing the recreational way for a while and then trying to switch mindsets. The course could be called "Advanced Deep Diver". It sits between the "Deep Diver" specialty and the "DSAT Tec Diver Level One" (previously called "Apprentice Tec Diver"). It's not a DSAT course because it stays within the recreational limits of no-decompression diving to 130 feet and air or Nitrox up to 40%.

Doc's transition course focuses on deep diving (between 70 and 130 feet) on air and Nitrox. You do these dives in a dry suit, so you get more dry suit practice as well. If you don't have the EAN, Deep, or Dry Suit certifications, Doc will integrate those courses into your training. In my case that meant we started the transition training with the dry suit and deep classes. Doc's background is in education and he seems to tailor his training to the students he's working with rather than trying to fit the students into a preset curriculum. In this way, his style reminds me more of flight training than traditional scuba training. Maybe it's a coincidence that he used to be Flight Instructor and an FAA Designated Pilot Examiner.

TDI was the certification agency that was recommended to me for tech training, but overall, the majority of technical divers seem to recommend finding a good instructor and to not worry about the agency since, in the end, they all teach the same stuff. The biggest difference between TDI and PADI/DSAT seems to be that TDI breaks up the training into a lot more courses. PADI basically has two courses, Tec Deep Diver and Tec Trimix Diver. (There's also the Tec Diver Level One which is really part of the Tec Deep Diver course and the Tec Gas Blender). TDI breaks this into "Intro to Tech Diving" (a brand new course similar to Doc's Transition to Tech course), "Nitrox Diver" (equivalent to PADI's recreational EAN course), "Advanced Nitrox" (covered in DSAT's "Tec Deep Diver"), "Decompression Procedures" (covered in "Tec Deep Diver"), "Extended Range" (covered in "Tec Deep Diver"), "Trimix Diver" (covered in "Tec Trimix Diver"), and "Advanced Trimix Diver" (covered in "Tec Trimix Diver"). TDI also has several overhead environment training courses that DSAT doesn't have, but I'll cross that bridge when I get there.

In any case, my next class will be spent putting together my tech rig, followed by a training dive to start practicing with doubles. That should be even more disconcerting than my first dry suit dive. Especially since I don't have that much experience in a dry suit yet.

I supposed the first skill a technical diver has to learn is how to dive in doubles. I get that opportunity this weekend. So, even though I had a brief taste of some technical dive training when we did the dry suit and deep diver specialties courses, this will be my first real technical dive training.

The dry suit class was basically just a recreational class except we were taught to use our suits tech style instead of rec style. That means we used both the dry suit and the BCD for buoyancy control instead of just the dry suit like you normally would in a pure recreational course. For the deep diver course, we practiced gas switching using a stage bottle hung at 20 feet (in standard recreational deep training the hanging bottle is just a bailout bottle in case you run out of air during your "safety stop"). We also did one dive using the tech diver rule of thirds to signal the end of our dive and then the final dive was done using run times and staged decompression stops (even though we were well within the no-deco limits). So these weren't really anything special: any recreational diver can do that.

This weekend, however, I'll be learning how to use a technical diving rig. This is a big departure from the standard recreational diving gear. In addition to having two tanks, the whole rig is different from the standard rec set up.

The first task is learning how to set up the gear, which we did this week. This started with connecting the two LP95 tanks together with an isolation manifold and tank bands. The tank bands are just metal bands that hold the tanks together and onto the rest of the rig. The tank valves and isolation manifold allow you to connect two regulators (one to each tank) and access the gas in both tanks from either regulator. Normally both regulators are drawing from both tanks. In the event of a regulator failure, you can turn off the valve to that regulator, but you are still getting air from both tanks using the remaining regulator. If, for some reason, you need to turn off the air from one of the tanks, you can close the isolation valve. Then each tank/regulator acts independently. I don't know know what situation that would be useful for, but I'm sure I'll learn that soon enough.

The next thing we did was set up the regulators. We used two Aeris AT400 Pro regs with DIN connections. The manifold is a Thermo 300 Bar DIN. You use DIN in tech diving because it's less likely to leak, especially if the connection gets knocked into something. Both regulators are high quality primary regulators. You don't use a standard octo in technical diving because the environment you are diving in requires that your backup be just as reliable as your primary. However, the second stage we designated as primary gets a seven foot hose instead of the standard hose. This regulator is connected to the right post and the hose routed down between you and your wing, then up across your chest and around your neck, left to right, and then into your mouth. The other regulator is mounted on the left post with the second stage hose going to the right and over your right shoulder. The second stage is attached to a regulator necklace. This holds your backup right below your chin, so in an out of gas emergency, you can hand off your long hose to your buddy and quickly pick up your backup. Both regulators get break-away clips. Basically this is just a gate clip attached to the hose using an o-ring and zip tie. If you have the regulator clipped off on a D-ring and you need it in an emergency, you can easily pull it off breaking the o-ring instead of fumbling with the clip.

Next we set up the harness on the backplate. The backplate is just a metal plate with holes and slots designed for routing nylon webbing to create the harness. We started with seven feet of two inch webbing which we routed through the various slots. In the process of doing this we added two D-rings to each shoulder strap and one to each waist strap. We added a metal belt buckle to connect the two waist straps and a plastic weight belt on the right side waist strap to hold the flashlight cannister (that I don't have yet). We finished it off by creating a crotch strap with a D-ring in the front and back, so you end up with four D-rings on your chest (two about shoulder level and two about three or four inches lower) and four on your waist (front, back, and each side).

Then we put it all together to see how it fit. Lay down the tanks with the tank band bolts pointing up. Put the wing on next with the bolts going through the appropriate grommets in the wing. Then put the backplate on the bolts and secure each bolt with a washer and wingnut. Next connect the regulators to the tank valves (long hose on right post and short hose on the left post). The LP hoses for the wing inflator and the dry suit inflator are connected to different regulators so you don't have all of your buoyancy on one regulator (redundancy). In our case, we are putting the wing inflator hose on the left post and the dry suit inflator hose on the right post. Additionally, the left post gets the SPG (with breakaway clip).

One other note. We removed all the hose boots. The reason for this is so we can see all the connections to look for cracks and leaks.

Comparing this set up to my recreational rig, it's simultaneously simpler and more complex. More complex because you have two tanks with an isolation manifold that you need to learn how to use. Simpler because there is not much to it. There is no integrated weight system, no fancy BCD inflation system, no adjustable tank strap that you have to set at the correct height every time you mount a tank. The tech rig is designed to be simple, redundant, and streamlined. Looking at a properly equipped technical diver, you will see that he's much more streamlined, in spite of the double tanks, larger wings, and other gear, than the average recreational diver. Recreational divers aren't general taught about streamlining, so they tend to jump in the water with all kinds of things hanging off off them. I know because I was one of them.

So the first think I learned from technical diving, streamlining my rig, will be an immediate benefit to my recreational diving.

This weekend we'll be headed for Gilboa Quarry for my first dive in doubles. This could be called my second dive weekend in the transition to tech course, since we started working on thinking like a tech diver during our dry suit and deep diver certification dives last month. In spite of the cold, it should be a good time.

When I started my dry suit class, everyone told me that learning to dive in a dry suit was like starting all over again, and they were right. So when I was told learning to dive in doubles is like starting all over again, I took it to heart.

The first thing about the technical rig (other than the weight of the doubles) is the change in philosophy. For one, in recreational diving, you keep your octo available for your buddy in an out of air emergency. You would only use it for yourself if your primary regulator failed. In technical diving, your two regulators are equal and you donate your primary to your buddy and take your back-up for yourself. This makes a lot of sense because in an emergency you want to make sure your buddy is getting a good, working air source. If you are breathing off of a deco bottle, handing your buddy the regulator in your mouth is your only option, so it's a good habit to get into. I guess the thought is that by the time you get to technical diving you are competent enough to deal with not having a regulator in your mouth for extended periods, so making sure your buddy has a good air source is more important.

Another difference is that technical divers focus on streamlining their rig. Recreational divers nearly always have things hanging down from them while they're swimming. Even if your octo and console are clipped off properly, the hoses tend to be long and looping, so they dangle. I used to always carry my dive tables on a ring with my dive slate. The whole bunch was clipped to a D-ring on my BCD, but when I was swimming, they hang. Recreational divers frequently snag their hoses on stuff. In tech diving, you focus on removing as many snag hazards as possible.

So before getting in the water, we check to make sure everything is routed correctly. Hoses are routed so they don't hang loose, everything that is loose is clipped to a D-ring to minimize danglies. Because you donate your primary regulator (the one on the seven foot hose) in an out of air emergency, you need to make sure it's not trapped by any other hoses or equipment. Double check your LP inflator hoses to your wings and dry suit. Make sure your regulators are functioning correctly. Once in the water, you check all of this again and follow it up with a bubble check of your buddy. A bubble check is basically just checking for bubbles coming out of your buddy's manifold or regulator connections. It's all about safety. Every critical piece of equipment is backed up. The primary and backup are double or triple checked.

So this is what I'm thinking about as we prepare for our first dive.

After checking and double checking everything, putting some air in my wing, and rubbing some defog on my mask, I was ready to get into the water for the first time. I followed Mike, one of the instructors, down the stairs into the water. With the crowd at the stairs, I made my first mistake: I decided to float out and put my fins on once I got away from the stairs. Well, it turns out I didn't have enough air in my wings and without my fins on (and no mask and no regulator in my mouth) keeping afloat while I found the inflator was a struggle. Fortunately it was a minor issue. A bigger problem was that trying to put on my fins while floating was a lot harder than in recreational gear. I was like a turtle on its back floating with legs out of the water. Live and learn, I guess.

Once we were all in the water and everything checked, we dropped down to the 70' platform for some buoyancy drills. First was the pin fivot. This is supposed to be the same as what you did in your open water training: get neutrally buoyant and then pivot on your fin tips as you inhale and exhale. Unfortunately, with the light fins I had on and the heavy rig on my back, I couldn't keep my fins on the platform, so it was more of an elevator than a pivot. Additionally, one strap was looser than the other, so the rig wasn't centered on my back. That made me want to roll over to my right. So my pin fivot wasn't very good. Next I had to get neutrally buoyant a couple of feet above the platform and float there. Finally, we headed off for the other side of the quarry. It was a nice long 55 minute dive that gave me plenty of time to get used to the new rig. The dive ended back at the original dock with several decompression stops (even though we were well within no-deco limits).

Our second dive of the day was a bit simpler. The plan was to dive to bottom of the quarry (120 feet), go to a submerged trailer, and then follow the north wall until someone reached their turn pressure. Well, we never found the trailer, but the north wall is impossible to miss, so we swam out and back along the wall, followed again by practice decompression stops. By this time I'm starting to feel pretty comfortable in the tech rig and operating the dry suit is starting to become second nature. All seems to be going well.

We woke up the next day to rain. The forecast called for rain all day. Now rain isn't a big deal when it's warm. But in northern Ohio in November, rain makes a cold day miserable. We decided that we would do our two dives back to back with a short surface interval.

The plan for the first dive was to demonstrate an S-drill. An S-drill is basically practicing emergency procedures. This one was to practice an out of air emergency. First Doc would demonstrate with Mike, then he would work with me. So we descended to the 70' platform and I dumped enough air from my wing to kneel solidly on the platform to watch Doc and Mike go through the drill. When they were done, Doc turned to me, signaled "OK", which I returned, and then gave the out of air signal.

As I said, in technical diving you donate our primary regulator on the seven foot hose and then put your backup in your mouth. To do this, you duck your head while pulling the regulator out with your right hand to unwrap it from your neck. This is why it needs to be free from the rest of your equipment. In this case, somehow my backup hose was covering my long hose. I had failed to fully check it at the surface. The result was that after donating my long hose, I couldn't get my backup fully in my mouth. I only had the left side of the mouthpiece in my mouth and running out of breath I had to inhale, which resulted in a lung full of quarry water.

Now, most scuba divers have inhaled small amounts of water at some point. It's not an uncommon thing, and even underwater, not a big deal as long as you have a functioning regulator in your mouth. But when you don't have a functioning regulator in your mouth, and you know it, and you're sitting at 70 feet below the surface, I don't imagine too many people who wouldn't have at least a moment's pause. Panic would not be an unusual reaction. Having just inhaled a nice mouthful of water and still not having my regulator completely in my mouth, and knowing that I'm at 70' feet, I had my first moment of real panic underwater.

What went though mind was something like: "Oh crap! Regulator's not in my mouth! I'm sucking water! Where's the regulator! I gotta get to the surface! NOW!" That took approximately a tenth of a second to flash through my brain. The next half of a second was: "I'm at 70', I'll never make the surface. My regulator is in my mouth, just not fully. Just relax, I can straighten this out out. The long hose must be wrapped around the short hose pulling it away from me. Pull the long hose away from Doc! No, don't do that, just try harder to get the back up completely in my mouth. Purge!" My hand was still on the regulator, so hitting the purge button happened pretty quick. That allowed me to get more air in my mouth along with more water, but now that I was expecting water I was able to keep from inhaling it. Still, I hadn't been able to cough yet because I didn't have the regulator in my mouth and I was afraid that if I coughed, I would involuntarily inhale while coughing which would make matters worse.

By this point Doc was well aware of my situation and he was returning my long hose to me. In fact, he told me later, he was getting ready to shove it in my mouth. I saw him offer a regulator to me (I didn't know it was my long hose, I just saw a regulator), but I didn't want to take the regulator that I had out of mouth, so I put up my hand to signal "wait". Since he was handing back my long hose, the stress on the short hose was gone and I was able to get the backup fully into my mouth and hit the purge button. I forgot to plug the mouthpiece with my tongue, so I ended up with more water in my mouth, but I managed not to inhale it and then I managed to get a full breath for the first time since taking my primary regulator out of my mouth. I think this was my third breath on the backup, so only a few seconds had passed.

Now I had myself under control, but I knew I didn't look like it, so I kept my hand up to let Doc know I was handling it. I wasn't OK yet, so I didn't want to signal "OK", but I needed to communicate something, so "wait" was the only thing that came out. He saw that I was responsive and coherent, so he let me handle, but he continued to hold my primary in front of my face in case I needed it.

After a coughing fit and a few seconds of breathing water free air I gave Doc the OK sign and switched to my primary regulator. Then Doc untangled my hoses for me, took my primary and wrapped it around my neck and everything was back to normal. The whole event, from the time Doc gave the out of air signal until I had all of my equipment back in place and I was breathing normally was probably only a minute, but it felt like a lot longer. I had two simultaneous thoughts: "I want to get out of the water" and "I hope Doc doesn't end the dive".

Fortunately, Doc is experienced enough to know "when to hold 'em and when to fold 'em" and with all the excitement over, he signaled "8-0" and "level off" indicating that 80 feet was our hard deck (maximum depth) for this dive, as we had discussed on the surface. I signaled OK and we swam off the platform. We immediately started descending and when we reached 80 feet, I stopped descending, but Doc and Mike kept going. I wasn't sure if he had changed his mind or if he was testing me to see if I would follow him below the hard deck. Doc looked up at me and I gave the "level off" signal, but he kept going down. I ended up descending a few feet below 80, but then Doc started swimming along the wall to the shallow side of the quarry per the dive plan, so I followed, keeping my depth about 80'. At the end of the dive, when we talked about it, Doc said he was testing me, but he was looking for me to come down and stop him. Next time, I'll know.

The rest of the dive was rather uneventful. We swam up to the shallow end past a submerged school bus and helicopter and through the cabin of a submerged plane. Then we practiced decompression stops and surfaced on the opposite side of the quarry from where we started. The first thing I did was cough out more quarry water. Then we debriefed, discussing the various events in the dive.

For the next dive, the goal was retrace our steps (or rather kicks) back to the deep dock, but with the short surface interval, we set our hard deck to 50' for the way back. Additionally, Doc wanted me to lead the dive. This was the first time I had lead a training dive, which was kind of neat.

Once we were ready to go, I signaled "descend" and we all slipped below the surface and began our swim back to the deep end of the pool. Part of the purpose of me leading was so Doc could see whether or not I could get us back. Fortunately, from our position, the route back was pretty simple. We were about twenty feet from the tail of the plane. The route back was to swim to the front of the plane, which gets you to the helicopter. There's a rope off the front of the plane that takes you past the helicopter to the school bus. Once you reach the bus, you are only fifteen to twenty feet from the deep side wall. Then you just follow the wall all the way back to the deep platform.

The trip back was pretty uneventful. Once we hit the deep wall, I kept my depth between 46 and 49 feet the whole way. When we got back to the deep platform (or at least above it, I signaled "up" and led us through the deco stops. I forgot to look at the time, so I was just guessing on the stop durations, so I need to work on that, but I went through the motions. It was, for me, the best dive of the weekend. It was also the shortest at 23 minutes.

After we surfaced, Doc and Mike critiqued the dive. They complemented me on keeping to the plan and checking back frequently, but they said I was kicking too fast. So I need to slow down.

All in all, it was a good weekend in spite of the weather and the small problem I had on the third dive. I'm starting to feel very comfortable in the dry suit and by the end of the weekend, I was getting very comfortable with the tech rig. The big things I learned this weekend were:

1. Always do a long hose check on the surface to make sure your long hose isn't trapped.

2. I still need to get some better fins for tech diving.

3. I need a lower volume mask for tech diving.

4. This was the first time I had used a wrist mount computer and now I don't ever want to use a console computer again.

Unfortunately, this was probably my last dive of the year, so it will be a while before I can put these lessons to use, but hopefully I'll have the right fins and a new computer by then.

One type of technical diving is cave diving. The thought of cave diving has never really appealed to me. I got into technical diving to dive wrecks. Yes, I know wrecks are more dangerous than caves, but psychologically being in a hole in the ground several hundred or thousand feet from the entrance just didn't sit right in my brain.

Then I took the Cavern Diver Specialty course. Cavern diving is similar to cave diving, but you need to be within sight of the opening and within 200 feet of the surface. Even with that restriction, you can experience quite a lot. You can do cavern dives with basic recreational gear, but I did the course in my tec rig, more for the practice diving in the tec rig than any other reason.

So I made the long drive to Florida just after Christmas to join Steve and Kelly Oborn on their annual winter dive trip to Florida. There were several classes going on during the week including some Open Water certifications and an Advanced Open Water class. The Cavern class consisted of me, Dave Brown (who got his OW certification the same weekend as my wife), Joe Tumeo from the shop, and Ed and Darcy Smith who got their OW certifications on this trip last year. Having five people was a little awkward, but it gave us the opportunity to practice working in teams of more than two.

We started the dive week at Devil's Den near Williston, Florida. The first dive was mainly an acclimation dive for most of the divers (although it was a training dive for the Open Water students). I dove in my rec gear the first day because doubles would have been way to bulky for the entrance to the sinkhole. During subsequent dives we practiced running lines and then following them out with our eyes closed. It was a relatively easy day. The real work started on day two.

The second day of the trip was spent at Blue Grotto, also near Williston. Blue Grotto is more of a cavern dive. We did more line drills including following the line out with mask off and eyes closed. This was probably the most disconcerting dive experience I've ever had, although I never felt uncomfortable. I knew I wasn't in any real danger, since in a worst case scenario I could just open my eyes and swim out and up, so I there was no anxiety, but I felt like I had somehow managed to get turned around or that I was sliding backwards down the line. In the end I made it out of the cavern area with no problems. It was a very good training exercise.

Our third and final day of cavern training was done at Ginnie Springs near High Springs, Florida. The first dive was to a cavern called The Ballroom. The entrance lies in about 10 - 15 feet of water. You pass through the upper chamber and a narrow opening down to The Ballroom. We practiced running a line from the entrance down to the back of the cavern even though there is a huge line permanently run there already.

Sitting (floating) in the Ballroom was incredible. Facing the back of the chamber our flashlights lit up some of the most beautiful structures I've ever seen while diving. It was incredible. Facing the front of the chamber you can look all the way up to the surface of the spring and the light filtering in reminded me of my first dive experience in the kelp forests off of Catalina Island in California.

When we came up from the first dive I turned to Doc and said "I'm hooked". The rest of the dives in Devil's Eye, Devil's Ear, and Little Devil only served to set the hook.

So now I'm going to start looking into getting full cave certified. I want to get some more tec experience first, but cave diving, once on my "never in my life" list is now on my short list.

This time a year ago I was busy chewing through the PADI Tec Deep Diver course work and thinking about how much information we were expected to know. We learned fun acronyms like "Being Wary Reduces All Failures", "a Good Diver's Main Objective Is To Live", and NOTOX. We learned how to plan gas consumption for divers with different breathing rates and tank sizes. We learned how to calculate decompression stops using gasses with different oxygen content. Most importantly, we learned how dangerous tech diving can be and how to minimize the risks, i.e. how to be safe.

One thing I quickly realized was that regardless of how much more depth or bottom time we would get by learning how to do decompression diving, my primary reason for getting into tech diving was still not being met. I got into tech diving to be able to dive wrecks in the Great Lakes.

The Great Lakes have some of the most well preserved shipwrecks in the world. The combination of fresh water, depth, and temperature allow wooden shipwrecks to remain intact long after they would have deteriorated or been destroyed in other environments. While studying for the class, I quickly realized that the 165' mark that the DSAT Tec Deep certification trains you for was insufficient to reach some of the best wrecks including the Daniel J. Morrell (a 587' freighter that sank in two halves five miles apart, the bow at 213' and the stern at 225') and the Roy A. Jodrey (a bulk freighter similar to the more famous Edmund Fitzgerald that sank a year later).

So that meant that I was destined to do the second half of the DSAT curriculum: Tec Trimix. The DSAT Trimix course teaches you how to plan and execute dives to 240' and beyond using gas blends of Oxygen, Nitrogen, and Helium.

If you're like me, the first time you heard of diving with helium, you thought someone was pulling your leg. As it turns out, helium has been in use in diving since the 1960s. Initially helium was used to replace the nitrogen in air (a mixture known as heliox) to eliminate nitrogen narcosis. Unfortunately, that introduced a new problem: HPNS (High Pressure Nervous Syndrome) when diving at depths around 400 feet. To counteract this, divers began to add nitrogen back into the mix to act as a mild depressant. Thus trimix was born.

So, the use of helium as a dive gas has been around for a while, and it allows you to dive deeper than an oxygen equivalent nitrox (nitrogen and oxygen) blend, but it comes at a price. Actually, it comes with several prices, including the cost. More important than that is the extra decompression time. Then the cost of a drysuit inflation system since you can't use trimix in your drysuit (helium doesn't provide enough thermal protection). Oh yeah, your deco stops have to be even more precise than with nitrox tech diving. And did I mention the cost of the gas? Oh, and sometimes you may be diving with a mix that doesn't have enough oxygen to support life at the surface. And you may be diving with three, four, or more decompression/stage/travel bottles. Using the wrong one at the wrong time could result in death. Not to mention just lugging all of that bulk through the water.

So why do it?

To get to the bottom. Honestly, the risks are manageable (even if they aren't eliminated) and replacing some of the nitrogen with helium makes you safer at depth because you aren't as narced as you would be with nitrox or air. And diving with hypoxic mixes (gas blends with less than 21% oxygen) reduces your oxygen exposure for even more safety. So you trade one set of risks for another. But you'll get to dive places that most people can't even dream about.

As for the inherent relative risk of diving to 245 feet versus 165 feet? Does it really matter? You can't go straight to the surface from either depth, so screwed is screwed. If you have an emergency that you can't handle the result will be the same whether you are 245 feet or "only" 165.

And to think that 130 feet used to be scary.