It's generally accepted that at about 217 feet air becomes toxic. Go deeper on air and do so at your terminal peril. A fast descent to about 200 on air with controlled ascent using recreational limits is totally dooable on a normal size tank as a first dive (i.e. no residual Nitrogen). The risk in this dive is the narcosis that you WILL experience. Tunnel vision. Potentially magical thinking. Lack of focus. Now, on their own these things aren't that big of a deal and can be fun, but when you are dropping like a rock and supposed to be paying ABSOLUTE STRICK UNWAVERING attention to your depth gauge, narcosis can be deadly. In sum, don't bounce unless you go with an experienced diver who understands the physiology and has some emergency diving experience.
Without reference to personal beliefs vis a vis whether bounces are dumb... Thoughts or concerns of a technical nature would be great.
I've done many short duration dives to a depth of around 200 ft on air. Reading your comments, I very much doubt that you have done anything similar.
First of all, doing any deep dive with a single tank (i.e., no redundancy) is risky and stupid, in my opinion.
Second, 218 ft on air is NOT poison. oxygen toxicity on your stated scenario is probably the least of your worries.
Third, leading people to believe that being accompanied by an experienced diver who has emergency experience is pretty silly, because if he is also diving on a single small tank at 200 ft - his ability to do much of anything to help is pretty damn limited.
Fourth, the misconception that you must concentrate on the depth guage is very, very bad advice. In fact, the exact depth is the least of your worries on such a dive. You need to be NOT focusing on ANYTHING and MUST be focusing on a lot of things simultaneously including: your exertion level, time, air pressure, dive buddy location and all the other things you are trying to accomplish during this bounce dive.
Fifth, you statement that tunnel vision alone is NOT that big of a deal is DEAD wrong as well.
So.. you got pretty much EVERYTHING wrong except for the statement that narcosis is dangerous at 200 on air.
Bounce diving on air to 200 ft is unwise and not recommended by any agency.
IF you are gonna do it, you need to slowly work up to it. Some people will NEVER, EVER be able to do it with any semblance of safety and self awareness. A lot better to find this out at 140 than 200 feet.
In any regard, you are going to be very, very hard pressed to find a responsible, experienced and a safety conscious mentor to accompany you on these sort of single tank, deep air bounces..
