Cave Diving, Cave Exploration and Cave Mapping in Yucatan, Mexico
Rebreather Diver at Chac Mool Cavern, Mexico

Category — Mayan Blue

Back on the loop

The advantages of a closed circuit rebreather in a shallow cave.

I have to admit that I recently neglected rebreather diving and instead spend most of my time off sidemounting. I pretty much used my rebreather for deep diving only. But recently that changed, I finished crossover training on the Poseidon Cis Luna Mk6 and right after that was with Howard, aka Scubadadmiami for a week of CCR Cave diving. And I am hooked on CCRs again.

Patrick Widdman on DPV and CCR

The Mk6 exceeded my expectations but this is not what this article is about. What I want to share here is my recent experience diving Ponderosa, Taj Maha, Nohoch Nah Chich, Grand Cenote, Carwash and Naharon. Generally all the dive sites have an average depth of about 30ft and Nohoch even being shallower with Naharon being the exception at 60ft.

In many posts on CCR forums, the Mexican caves are described as CCR “unfriendly” and honestly I do not understand why? Our recent experience illustrated that CCRs can be used effectively in these caves and enabled us to get to know whole sections of systems in only one dive.

Normally when I guide people open circuit I choose a cenote and then guide two dives to the most famous or pretty parts of the system. The dives are usually turned either on time or gas which results in returning to open water. The option to recalculate thirds does exist, however, my opinion is that it should be reserved for experienced divers with experience in the particular system. When divers elect to recalculate thirds, eventually the gas reserve becomes to small to be safe.

The advantage of the CCR is that you have a bail out radius which enables you to spend as much time as the scrubber will allow, normally about 3 hours which is a huge opportunity here in the Riviera Maya.

The cave systems here are like Swiss cheese with many different side tunnels and passages. They are also very shallow. These two characteristics combine to create a situation where divers have a very long range on an 80cuft cylinder. Depending on you gas consumption while bailing out and conservatism factor you want to build in you will have a radius of at least 40min in most places. There are other benefits worth mentioning:

  1. Once you come of the frequent traveled passages you will often encounter quiet significant amount of percolation that can seriously affect the visibility.
  2. Thinking about the lost line or lost diver scenario, imagine how your chance of survival or the chance of finding your dive partner will increase with an hours long supply of breathing gas.
  3. How many accident reports have we seen that speak about people drowning only minutes away from an exit, what would have happened if they would have been on a rebreather.
  4. Taking pictures on the way, on a CCR you penetration distance is not going to change because you stop at a place to take some pictures or simply take a brake.
  5. Think about a reverse block way back in a cave, how much more relaxed are you going to be, knowing you can stay there fro hours.
  6. No time or gas pressure to go to a certain part in the cave and therefore reduced chance of pushing limits due to being goal oriented.
  7. And many more

Of course this is a double edged sword and there are as well some negative aspects:

  1. Buoyancy is definitely more difficult.
  2. It is the perfect tool to bring people that where before limited by their air consumption far into the overhead environment and by that outside of their comfort and experience zone.
  3. With most units together with the bail out your overall size in the water column is bigger and therefore you need more effort to travel.
  4. Many ups and downs consume Oxygen and Diluent volume.
  5. Getting overconfident due to the feeling of having unlimited gas supply.
  6. Proper bail out gas and volume is never an issue until it becomes an issue.
  7. And many more

To have a real advantage with the CCR we have to change the way we dive in the cave. Instead of using it to go for that record braking long distance penetration why not stay closer to the entrance but get to know all the lines that are in that area.

For example, at Naharon we dove up the main line and did the Jump towards the double domes. We swam up that line until we reached 40min, or bail out distance. On the way we stopped several times to take pictures and simply stopped the timer while we did not go further in the cave. On the way we marked the double set of line arrows that mark the jump towards south western sac be. On our return we arrived back at the arrows and new that from this point on we had 30min for further penetration so now we did the jump and enjoyed the really unreal beautiful sac be section.

On the way there we pass yet another set of double arrows marking the jump that lead down towards Cenote Mayan Blue and again marked it. We continued in the sac be tunnel until we had reached 30min from the jump and turned our dive. On the way back we stopped again a couple of times to take pictures. We didn’t even have to take care about the time since we were well inside our bail out range.

Howard pushing a tank through....

As we arrived back at the Arrows we decided to make yet another jump and check out the line that leads towards Mayan Blue. After some time we turned from there and now did the entire return trip back to Cenote Naharon.

As you can see, we did in one dive what, in conventional OC cave diving style would need three dives. We had an average depth of close to 60ft with a 180min runtime, me carrying an 80cuf and Howard 2 40cuf bail out tanks.

Another example would be Carwash where we could use Lukes Hope to restart the 40min bail out range and therefore had plenty of time to visit the room of tears and all the different Ts in the back. On the way out we did the jump that leads to the back of the room and stayed there for like 30min just doing pictures and enjoying the decorations.

In Grand cenote we went down to the Cuza Nah Loop and could restart the 40 min each time we past a cenote which was awesome since this gave us the possibility to do the jump at the mid way of the loop and take our time while swimming down that line again taking pictures and having a great time. On the way back we continued the loop on the other way since we were still easy inside our bail out range.
And the same was done in all the other places.

All in all I really enjoyed this week especially the possibility to visit lines I have not been too in a long time. I really love to do complex navigation, see different lines and go back and forth and all around.

Another bonus, so to speak, was to get more experience on the Kiss Classic which I really start to like more and more for its simplicity, the 20min prep in the morning and the 5min tear down in the evening, the free chest, constant O2 flow which facilitates buoyancy and the general possibility to keep the same configuration than with a set of doubles.

For Howard it was great too because he really got to know quiet a bit of each system we dove at, although he only did ONE dive there.

Considering all of the above, I would call the caves here perfectly suited for CCR diving if you bring the right set of skills, a good attitude and some creativity to the table.

Of course there are always people that say OC backmount is the only way to go and others believe that OC sidemount is the best, then there are some that believe in multiple stages or scooters or I don’t know what else; Me, I think it all has its use and its just what you do with it that makes it valuable. Try to get the most advantages out of whatever equipment you use and try to work with the right tool for the job!

Keep the loop closed but your mind open!!!


July 25, 2009   4 Comments

Circuit at Mayan Blue

Learning to not waste gas setting the primary reel.

A couple of weeks ago, I did an awesome single stage dive down Tunnel A and out to the end of the line past Maya’s Two Cenote and Lost Cenote.  In the weeks leading up to the dive I was feeling flat and burned out.   Probably from doing too many dives that required too much preparation, work and stress.  That dive really turned things around and refreshed me.  The highlight of the dive was the blue water in Hostage Hall.   I don’t know; I just had a ton of fun.  When Alain and I decided to dive today, I knew just where to go, Mayan Blue.

It was Alain’s first trip to Mayan Blue and I had an excellent dive in mind.  Patrick had been bugging me to do the do the circuit that passes through The Tubes and then up through The Dead Zone.  I thought I would finally oblige him.  Luckily, on the aforementioned dive I had done about fifty percent of the circuit so I sort of knew what to look for to connect the loop.  I remembered a red arrow that said Sun Cenote on the line coming down from the Dead Zone.  That was my mental clue for knowing where to connect the lines.

It has rained for the last 35 consecutive days.  This has flooded some of the cenotes. When we arrived at Mayan Blue the water was 1ft over the deck and the water was tannic down to about 10ft (3m).  I really hate jumping into tannic water, I always feel like there is going to be a scary monster in the water that is going to reach up and bite me.  I am sure you know exactly what I am talking about.  I overcame my fear and we started the dive from The Dead Zone entrance.

I lead and Alain staged a bottle of 02.   I had been in that section before so finding the main line was pretty easy.    We estimated it would take us 7-8 minutes to get to our first way point, the sharp right hand turn where the tunnel turns south and drops down to 60ft (18m).  We reached it in 9 minutes.  We were close to schedule but I still wasn’t sure if we would make it to our objective, the jump to line leading to Maya’s Two Cenote.

I am going to digress for a minute, but I suffer from a terrible waste of gas when setting the guideline to open water.  For some reason, I always seem to burn 500psi out of one tank for that small task, even when the main line isn’t that far from open water.  Setting the reel drove my SAC through the roof and would blow out my estimates for the entire dive.  It was really frustrating!

For a brief moment I considered carrying a small stage just for setting the reel.  I know it is ridicules, but it was awful and embarrassing to waste that much gas at the beginning of the dive.  I knew it wouldn’t fix the problem only the symptom.  So, I decided to talk to Steve about it during dpv/stage class.  I explained to him what was happening and how frustrated I was.

He suggested that after prepping for the dive and getting all worked up entering the water I was a little stressed.  He asked me how I felt when I started most dives and I told him stressed and anxious.  His guess correlated nicely to my experience.  He suggested that after everything is ready to go, I take 5 minutes, float on the surface, and focus on relaxing and breathing.  Take some time and just chill out.

He also suggested that setting the reel added to my stress level and I was forgetting about my breathing.  The cumulative effect was why I was wasting so much gas.  I agreed with him.

With that knowledge I decided to put his recommendations into use today.  Once Alain and I were completely ready to dive, pre-dive checks and all were complete, we took five minutes and just floated there.  I took some time to meditate and relax each muscle group on each exhale.  It felt great.  The stress and anxiety of the coming dive melted away.  I cooled off a bit and started to breath with a nice rhythm.  I just felt so much better.  Thank you Steve!

Setting the reel went really smoothly and I used about 50% of the gas that I would have normally used for a run that long, I think about 250PSI.  I made my breathing the first priority, buoyancy with the BC next and setting the reel number three.  I was really satisfied with the change.  Everything just came together.

The swim down from the turn is really beautiful!  There is big cave, small cave, restrictions, and silt.  It is perfect cave for sidemount.  I can only think of two places I needed to turn 90degrees to fit through a restriction, the rest of them would have been tight in backmount.  When we reached the first potential connection point, it was 19 minutes.  We found a green arrow and a pretty big jump. I swam across and put a cookie on the end of that line and returned.  I was pretty sure we weren’t in the right place yet.  The arrow on our line was pointing wrong direction and it was the wrong color.  Unfortunately, those two indicators can’t be trusted here.  Lines and arrows change in Mexico ALL the time.  I wrote some notes on my survey slate and we continued.

We passed a couple of more arrows and a change in direction.  None of those were candidates because they were jumps in the wrong direction.  Were having a fabulous dive!  We finally came to two red arrows that said Sun Cenote.  I looked right and the jump was about 2ft.  I felt like we were in the right place and the time reflected it at 36minutes.  I signaled Alain and asked if he wanted to make the jump.  He said yes and told me he has about 200psi to burn between his tanks.  I signaled him I had about the same amount of gas and I just wanted to go a little ways, he affirmed, I installed a small spool and we crossed.  We swam a couple of minutes and I started to recognize the cave, I felt confident.  At 40 minutes it was time to turn the dive and I placed my cookie.  We agreed to use 900psi and we hit the mark about the same time.  I was stoked knowing that we had jumped onto the correct line.  We exited leaving our markers and reel in place.  The exit only took 31 minutes, Alain picked up the pace after accusing me of being slow.  We used even less gas on the exit.

During the 2 hour surface interval we tried to figure out where on the map we made the connecting jump.  We never really did.  Either the distances are wrong or I am just confused.  Alain and I decided we were going to try and complete the circuit.  We agreed that when we reached my cookie, we needed to have 2000psi left.  This added 200PSI of conservatism.

We entered the water and we repeated the relaxation routine.  It was awesome, I felt great.  We put the primary reel in A Tunnel wasting little gas and made the first marked jump to the left.  We passed Maya’s Two Cenote at about 10 minutes and dropped down into The Tubes.  The dive was going great.  In fact, this dive was better then my first dive to the tubes.  The first time I was in very limited visibility the entire time. Don’t accuse me, I found it that way.  This time visibility was great and now that I could see the floor, I was amazed how bad the floor in The Tubes is damaged.  It looks like there was a bar room brawl down there!  People, please be more considerate and practice some cave conservation.  If it is too small and you can’t stay off the floor, stay the fuck out.  This is equally true of Minotauro.  It is going to take centuries or more to repair your damage.  There is plenty of cave that doesn’t require you to be that close to the mud.

We made it to the T at Lost Cenotes in about 25 minutes.  I wasn’t sure how much further it was to the marker.  The first time I came this route I had checked all the jumps and really wasted a lot of time.  I was surprised when we hit my cookie at about 30 minutes.  I had used 600psi out of each tank, so we had plenty of gas.  Alain and I did all the appropriate confirmations and decided to finish the circuit.  We gave each other a high five.  I have to admit that it is comforting to come up on your own gear and confirm you are going the right way.  We finished the circuit at 60 minutes and with 1500psi remaining in each tank.

We did a short stop and swam over to A Tunnel.  We dropped down and went to pick up our gear.  I had placed a cookie at the T in Maya’s Two and didn’t want to leave it.  When we reached the end of the clean up we were at 94 minutes and I had 10 minutes of deco on my Suunto D6, Alain had no deco on his computer.   He did a safety stop plus two minutes and surfaced. When he got to the deck there was a 5ft black and white snake sunning itself.  Alain was trapped in the water.

When my computer finally cleared it was 109 minutes.  I love deco minutes on dive computers, talk about bending space time.  I swam to the wrong end of the cenote while decoing, so I had to surface swim back.  By the time I arrived the scary monster had slithered into the water and disappeared.  We celebrated the dive, cleaned up and headed to Tulum for some chicken at Pollo Bronco.  It was another excellent day with a great friend and dive buddy.

This is a fantastic circuit, but it takes all day to setup, complete and clean up.  If you want to dive it, I recommend getting some Nitrox 32.  That would keep you squarely in the NDL limits.  Also, care has to be taken if you are diving in backmount or with a stage.  There are some tight areas that can easily be damaged.  Lastly, a big percentage of this dive is in the halocline, so be considerate of your dive buddies.  I would really limit the team size to two.

October 26, 2008   3 Comments

8000 Feet, One Spool and One Total Loop Failure

A traverse from Naharon to Mayan Blue on rebreathers.

This past week has been very busy for Patrick and me.  With the arrival of “Slow Season” here in Playa Del Carmen, we have found more time and more opportunities to get ourselves into some serious dives.  We have made two trips to The Pit and one trip to Sistema Naranjal with our Megalodons.  Luckily, the dives at The Pit were relatively excitement free, other then Patrick reaching the restriction at Jill’s Chamber at 105 meters.  However, the dive at Naranjal was anything but boring.

Patrick had finished up a full cave class at Mayan Blue on Sunday.  Unfortunately, the student didn’t complete the A Tunnel / Death Arrow circuit, so we had to retrieve the remaining gear, one spool.  We decided the only reasonable way to do the clean up dive was to traverse from Cenote Cristal (Cenote Naharon) down to the Death Arrow jump, pick up the spool, and swim back.  The swim from Naharon to Mayan Blue typically takes about 2 hours.  We decided to cut the swim a little short by only going to the end of the Death Arrow passage.

When we were planning our bailout gas, I was worried about having enough.  I hadn’t swum this distance and I wasn’t sure of the depths.  Patrick and I agreed to take 2 Aluminum 80’s each.  We ran some calculations and it was enough to get us out if we needed it.  Patrick’s calculations showed that two 80’s would last him 4 hours at this depth.  My SAC is higher, so I didn’t have same cushion.

When it came time to decide on our gas mixes, I asked Patrick what he was taking?  He told me Air.  And then we got into a discussion about bailout.  He very sternly explained to me that the choice of bailout gas didn’t really matter.  He didn’t believe he would ever have to bailout.  However, if he did he would only be punished with deco time.  He explained that he follows a checklist and is meticulous about assembling his unit.  I told him I was going to take 32% regardless of his feelings on the topic and I was going to drop a tank of O2 in the cavern for good measure.  You really never know when something unexpected is going to happen.  Isn’t that the definition of unexpected?   We agreed, or I decided in my head, I can’t remember, that if someone bailed out, they would get the 32% and the Air would be the gas of last resort.  At this point, Patrick’s attitude really concerned me and I decided that I was going to have a sit down with him, but I was going to wait until after our dive, as to not mess with his head.

Wednesday arrived and we got on our way.  The dive was going according to plan.  We passed the restrictions heading for Mayan Blue.  At the T, I wanted to “drop” a cookie.  As I got my markers out of my pocket, I dropped my safety spool. I reached for the safety and lost control of my buoyancy and started to fall.  I reached for the inflator, but no luck!  I ended up rolling down the windows saving myself from crashing into the mud, but creating some silting.  I could hear Patrick laughing as he watched this comedy of errors.  I finally got my act together, marked the T and proceeded.  I am sure it looked hysterical, you know how things happen in super slow motion, I know I was laughing about it.

We arrived at the spool at 80 minutes.  He retrieved the spool and we rested briefly.  When we finally got going on the return trip I was in the lead.  We were singing into the DSVs and just enjoying the dive.  After about 10 minutes we settled into a decent rhythm and pace.

At about 20 minutes, I saw a quick flash of the light head of me.  I instinctively turned and started to swim to Patrick.  We were about 50feet apart.  It took me a second to process the situation.  What I saw was one of the breathing hoses from the KISS Classic just floating in the water and I saw Patrick deploying a bailout reg.  My first thought was, ‘Oh shit, what do I do?  My bailout regulators are really secured and are not quickly accessible.’  Before I was close enough to help, he got his regulator out.  I arrived and assessed the situation.  The exhale breathing hose had disconnected from the canister.  At Patrick’s request, I reattached the hose.  We thumbed the dive, changed positions and started swimming.  This is when my heart rate finally picked up and I became aware of the gravity of the situation.  This was a real live catastrophic loop failure way back in a cave.  This is the exact type of unexpected situation we train and prepare for.  I knew we had enough gas, but I still got hit with some adrenalin.  I had to stop and think about my breathing and heart rate for a second.  My heart rate really isn’t under my control sometimes.  The base of the brain just reacts.

As we swam, I stayed near to Patrick in case something else went wrong.  I checked my computer and marked the time.  We had 60 minutes of swimming up stream to exit the cave.  Patrick cleaned up his hose routing and attempted to go back on the loop.  As I watched him attempt this, I just kept thinking, “You can’t recover a KISS from a total flood.  Don’t try.”  He found out in short order it was a done deal.  Then I offered him my 32%.  He waved it off, and he started to play with his X1.  Patrick later told me he thought he would be fine on air.  However, a couple of minutes later when we reached the T, he realized he was running out of no stop time and asked me for some 32%.

He asked at the worst time for me.  I was about to pick up my cookie and had too many things going on at once.  I struggled with my tank for a minute and finally told him to start swimming.  It would be easier to make the switch underway instead of hovering.  At this point I made a mistake, I think I was a bit overloaded and my brain was fried.  Instead of doing one thing at a time, I had the tank neck out of the bungee in the left hand.  I reached down to get the cookie with my right.  Now I was swimming with both hands full trying to get my tank completely off.  Ug! What a nightmare!

I finally stopped and stowed the cookie.  Then I passed the tank to Patrick.  He reached down to pull the regulator off the tank and the mouth piece came off!  The irony is that Patrick recently told me it was stupid to put the bungee necklace under the same zip tie as the mouth piece and that the mouth piece would come off at the worst time.  I defended my choice and didn’t change my configuration.  The bungee was wrapped around the tank neck and under the single zip tie.  When he showed me the regulator without the mouth piece, I could hear his voice in my head and I laughed.  I have since changed my configuration for CCR diving.  I removed my 120 degree swivel and the necklace on the bailout regulators.  I want them to be as accessible as possible.  Now, I believe that I will need them at the worst possible time.  He replaced the mouth piece and started to enjoy the joy that is 32% EAN.

Patrick swam off and I struggled with his tank.  This dive taught me my sidemount bungees are too short to be useful in an emergency.  As I struggled with the tank, I swam into the ceiling with my rebreather.  It got a little hung up so I jerked my head down.  I immediately realized my head was way heavy and I was heading for the floor!   A huge rock had broken loose and was on its way to pinning me.  I rolled to the right and the rock fell off my head before I hit the ground.

Again, I laughed.  I couldn’t believe how many things had happened to us on a single dive.  We have been diving for seven months together and all of those dives had been incident free.  A series of walks in the park, including cave dives to 300ffw.  The type of diving that breeds complacency.

I caught up to Patrick and we continued to exit.  We decided to pull our gear.  As I pulled my spool from the jump between Southern Sacbe and Southwestern Sacbe, I created a nasty knot around the main guideline.  I ended up cutting the spool free from the guideline.  It was the last in a row of incidents.  We exited safely with a total run time of 180 minutes.  I estimate the total distance at around 8000 feet.

Patrick and I agreed that we handled all of the situations acceptably.  We did a serious review of the dive and have both made changes to our rigs and attitudes.  As I mentioned, I changed my regulators and I lengthened the sidemount bungee.  Patrick also made some changes to his regulators to ensure they are accessible.  We adjusted our bailout gas attitudes.  And we agreed to take better care to avoid team separation.

Once the stress started to pile on, it made simple tasks like a tank swap more difficult.  A task he and I normally can handle in a minute or less took a couple of minutes.  My overall awareness decreased and we got a good distance apart more then once after the main failure.

I feel it was an excellent dive!  We both returned and no one was hurt.  We tested our abilities as a team, and as individuals in a stressful situation.  We both stayed calm and controlled our breathing.  We reacted instinctively and completed the tasks at hand.  We realized our performance wasn’t perfect but it was acceptable. The whole dive confirmed to me the following idea.  Bailout is for unexpected situations and it does matter.  No matter how bullet proof you might think you are or your procedures, unexpected shit happens and it will happen at the worst time.  And these situations never happen alone, they are always compounded by other events.

Patrick used just over 2000PSI from one Aluminum 80 to exit from 60 minutes into the cave.  I hope you learn a little from this, I know I have learned a lot.

As always, your comments and criticisms are welcome here.  If you want to know more about the incident, leave a comment and one of us will respond.

July 29, 2008   13 Comments