Too tired, and too many divers

[LCF]

Last November, four of us signed up for a day of guided diving at a shallow system in MX. All of us were Full Cave, and three of the four had significant experience, ranging from hundreds of dives at that level to at least a couple dozen. One diver had newly achieved his Full Cave rating on this trip.

We were doing a single stage dive into a system new to all of us but the guide. The plan was simple. We would enter, go to about 25 minutes, take a short side passage and admire it, and return to the mainline. We would then continue up the mainline until we reached turn or the next cenote, whichever came first. We were told the next cenote would be about 90 minutes in.

The first part of the dive was uneventful. We entered, reached the jump, swam the side line (which was beautiful) and returned to the mainline. We then swam about an hour along the main tunnel, which was spacious, and the diving was easy. At that point, the cave shrank down to much more of a tunnel, and began to zig-zag. The guide and I reached a T and marked it and swam a little way down the new line, when the guy behind me signaled me and I turned around. He was alone behind me, and indicated we needed to turn back. We did.

It was a four minute swim back to reach the other two. They were waiting in the main tunnel.

We exited, and I was miserable throughout the entire hour plus swim, trying to figure out how I could have gone four minutes without noticing there was no one behind me.

In the parking lot, we discussed the issue. What had happened was that, shortly after entering the smaller section of cave, one of the rear pair had reached turn pressure. He had signaled the guy in front of him, who had stopped without passing the signal forward. He received the "time to turn" information, turned around, and we were gone. He had to swim forward to catch and stop us, and in the meantime, the rear buddy pair returned to the main tunnel.

Issues:

1. Too many divers for a team. Three works; four is manageable if everybody is very aware. Five was too many.

2. Unfamiliarity with the system. If the rear pair had known that the cave was going to get and stay small, they would have turned the dive while we were still in the main tunnel.

3. Fatigue. I had been watching my timer and thinking that it was time to turn the dive on just swim time, but I knew we were near the next cenote, and didn't want to cheat the other guys out of getting there, just because I was getting tired. (I wasn't near turn pressure.) What clearly happened was that I slowly got just focused on following the guide's fins, and lost awareness of what was going on behind me.

4. Coordination. While the middle guy was chasing us, the others moved back. This created the illusion of an even greater team separation than had actually occurred, and left me frantic, feeling I was responsible for it.

5. Communication. When the rear team signaled, the signal should have been passed up the line. That would have stopped everybody at the same time. (This is an error I've made several times in the past, and it's an easy one to make -- you get the signal, and turn around to see what it is, before passing it along. Then, when you have the information, the folks in front of you are no longer in a good position to give it to.)

Nobody got hurt; nobody was even at risk. But they could have been. And I learned a real lesson, and haven't pushed a dive like that since.

[aainslie]

FIVE??? Sheesh... Two feels crowded these days.



On my first ever real cave dive (intro) I scared the crap out of my instructor by running off on my own and leaving everyone behind. I kept circling my light and my narced head kept telling me that someone was circling behind me.

The King was emphatically not happy.

[w ripley]

Thanks for the post. Several of the points you made are familiar to me. I agree with AA and believe many of us prefer solo dives for reasons both of you listed. The size of the team in a "clear system," like you normally find in Mexico, vs the "less cear sytems" like we usually find in FL have a lot to do with the size of the team. 3 is the max for me in FL unless just going up the main line in Ginnie, etc., and I'd prefer 2 or 1.

Anyway, good read.

[RN]

I won't dive in a team larger than 3. If there are more, teams are split into 2s and 3s. Even if you were paying more attention, it takes way to long to relay a signal up 5 divers and separation would still have been likely. The only issue I see in this incident is too large a team.

[LCF]

Too large a team was definitely one of the issues -- had we simply considered ourselves a team of two and a team of three, the two could have turned back without issue.

But the issue that was the lesson for me was fatigue. It was very clear to me that I had gotten more and more tunnel visioned, as my focus went internal, thinking about how my body felt and how much further I wanted to swim, and how long was it going to be to the next cenote. I had stopped paying diligent attention to the light behind me without realizing it. In Mexico, it is very easy to do extremely long swim dives on backgas or a single stage. The lesson I learned was to turn a dive while feeling GOOD, not when I'm already fretting about how long it is to get home.