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Throw a Thumb at it

Our first choice of caves today said, "It's the high season. Too may swimmers. No divers. Come back in summer."

Our second choice already had enough divers setting up there that it would make getting in and out (and an expected bit of deco) quite uncomfortable.

So we wound up diving Plan C. Which means plans were already a bit, "We'll take things as they come." That said: we put together a solid little tour of the cave and got underway.

Until we hit a point that I remembered being much bigger than it actually was. Or, more likely, the last time I was there was on sidemount and it just seemed much bigger than in today's backmount all around. So we turned.

On the way back we decided, "We're so close to the exit, let's recalculate and head down this other little jump."

I knew I'd been there before but, truth be told, I couldn't tell you when or what was that way. But the two people I'm diving with are as solid divers as there are and don't have much to prove. So the quick metric in my head was, "They'll either be able to handle whatever we find or be chill enough to call it if they don't like it."

It wound up getting called. And rightly so. Primarily because of communication... or lack thereof.

The breakdown in communication wasn't really anyone's "fault" per-se. This was only the second time I've ever been in the water with these divers: they still don't know know me and my diving well, just as I don't know theirs. And the place did not exactly make communication easy.

The blue arrow is direction of travel. The brown (sort of obviously) is rock. And the black is the route of the line. We're looking (also sort of obviously) from overhead. Since we're looking from overhead it is hard to illustrate that this entire area is just a little 30 foot section of line through a low, silty bedding plane. And when I say low... no more than 3-4 feet from floor to ceiling the entire time... sometimes pinching to just enough to let a diver in doubles through.

It's also right in the halocline. So I'm bouncing along, it being impossible to be neutral right at the salt-fresh interface, in the first position, trying my damnedest to stay as far away from the line as possible in these narrow, low areas so that the two divers behind me can see a damned thing. And I'm wondering to myself, "I don't think this opens up... I think it just stays like this... fuck."

When I see that window to my left in the illustration. I can clearly see that the line makes an odd turn, there's no T or anything, and if I go through that window it leaves the line totally clear for the divers behind me to have a little respite where they'll be able to see something for a change.

So I signal to the diver behind me by tracing the line with my light as I swim through the window. I see their light follow mine, and then the diver follow me through the window.

And that X is where diver three stopped dead, refusing to budge another inch.

Because after two divers had passed through that point, between the silt and the halocline, diver 3's visibility was severely inhibited. And from their point of view... the line went right, into more shitty viz... and the rest of their team had just randomly swam left, straight away from the line.

A few seconds later I get a flash from diver 2. We both turn to see the glow of diver 3's light hovering motionless some 20 feet or so behind us.

I think we both knew what had happened at the same time. There was no way to have this conversation where we were. And no point... I was pretty sure the cave just stayed like that. I signalled turn around.

When we got back to diver 3 they gave us the divers' universal "WHAT THE FUCK WITH YOU TWO?!?!" A thumb.

We debriefed it. Diver 2 had tried to signal to diver 3, "Hey look! Visibility for you over there!" before following me through that little window. But we had both failed to anticipate what such a movement through the water would look like from their perspective.

Add to that that we were already bending the phrase "dive plan" to its breaking point, in a cave that the two other divers have never seen before in their life and in a section I didn't remember well...

Damn right it was the correct call to thumb the dive at that point.

We've all got those dive buddies we barely ever need to communicate with. Sometimes it's just a glance or a shrug or a private hand signal that can communicate volumes. Or those buddies where the single thing you communicate during an entire two hour dive is, "Turn pressure."

We've got those dive buddies we trust absolutely after dozens or hundreds of dives.

We've got those buddies who know the site backwards and forwards and aren't going to lead you astray.

But when it comes to some of these advanced levels of diving... it is always, absolutely, the entire team's responsibility to check and double-check every segment of the dive.

I've been on dives with those sorts of buddies, not just good buddies, but some of the best divers in the world.... when they've missed Ts. Or accidentally jumped to an absurdly run, nearby line.

Even with your absolute best dive buddy: Trust... but verify. Communicate that verification however you do as a team (passively, actively, by having a board meeting, whatever).

But anytime something doesn't add up:

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