Chances are pretty good that if you still bother reading any of my drivel it’s because you’re a diver. And, as a diver, you’ve got it in your head that, given a choice, you would be underwater all day every day. Of course you would. It’s your happy place. It’s where you feel calm and peace and wonder. It’s a place of enlightenment and abandon. It’s a place of meditation and relaxation. Why wouldn’t you want to be underwater every minute of every day? Because we’re not built for it. That’s why. This is going to read like a challenge for some people. It shouldn’t. I’m not questioning your commitment to diving or your abilities as a diver. You have nothing to prove and there is no such thing -in reality, as opposed to in some heads - as competitive scuba. 180 minutes. In my experience, which is of modest comprehensiveness, 180 minutes is the vast majority of people’s breaking point. I’m not talking about over the course of a day. Divers on a liveaboard might far surpass that number. Hell, in two dives here you’re almost certainly going to far surpass that number. But in a single dive, at about 3 hours people’s concentration starts to break down. Nor am I talking about deco. It’s actually fairly easy to endure hours of deco provided you’ve got a good magazine or some way to watch a movie or three. I’m talking about actual dive phase of a single dive. Swimming. Especially as a cave diver you need to be absolutely focused for the duration of the dive. Buoyancy, trim, propulsion, team awareness, light discipline, gas management, referencing the cave, keeping track of navigation, keeping track of waypoints, constantly running through mental math, constantly listening for anything that might just sound a little off, and on and on and on and on… There is a lot going on, and that’s besides the physical strain of keeping your body in a position we’re not evolved for, the thermal stress, the decompression stress and on and on and on again. The emotional and psychological strain that comes from trying to maintain that level of awareness and attention for that long is incredibly challenging. I hit that wall myself. At exactly that time. I’ve been on dives where the actual dive phase is 5 or 6 hours. But at hour three I need to communicate to my team, “We need to stop and I need to just float here for a moment and reset.” If I don’t my mind starts to wander. I start to focus on odd things. I start to doze off (seriously… I have fallen asleep underwater. Many times, actually). And, in losing that level of focus, I run the very real risk of missing navigation or not noticing that someone in the team is having a problem… perhaps not noticing that I have a problem. Lest you think this is bias, that I’m basing my 180 minute hypothesis on my own limitations… I honestly can’t even recount the number of people I’ve seen completely forget how to scuba dive at that exact time. People lose control of their drysuit or stop paying attention to CCR loop volume. They might follow any line that crosses their visual path, accidentally blind jumping repeatedly. Or folks who simply stop swimming… they move their feet around a little, but don’t really go anywhere. Again, and I can’t stress this enough: This is not a challenge. I don’t care if you’re one of the weird ones who can dive with laser focus for 8 hours straight. There still isn’t a medal for that, nor is there likely ever going to be. Take it, if indeed you’ve read it at all, as a suggestion. Plan your long dives with a swim time of around three hours. At the very least, your back will thank you.