Hank49
Contributor
30-40 feet? It sounds like you're planning on spear fishing?
I find that to be an awkward depth where I break the rules I learned in my PFI (Performance Freediving Instructors) class. You will likely learn from FFD that you should be positively buoyant at 30 feet. This is so that if you do black out at 10 feet or so, you'll float up instead of sinking.
But I do hunt frequently at that depth here because the cuts with high current are 30-60 feet or so. I overweight so I'm negative at about 15 feet if I want to lay on the bottom at 30. That gives me more bottom time because I don't have to work as hard to get, or stay at that depth.
The keys for me in diving better to that depth were/are, stationary bike for aerobics helped a LOT. Don't eat the day you're diving other than a couple bananas in the morning. Digestion takes oxygen and a full stomach takes up space. I use a neck weight, which keeps my head down, going down and staying down. Relax on the bottom. Let your head drop down. The fish will come to you.
And no matter how many times it's been said, if you're pushing it, make sure you're diving one up, one down with a buddy. I know this is safer but I am guilty of diving more or less alone though. It's easier to be a sneaky bastard when hunting alone. But I also don't push myself. I ascend way before I'm getting contractions or really feeling a need to breath.
