[maytag]

One thing to really worry about would be a silt-out -- especially with long fins in a an overhead environment with low clearance. This could make it very difficult to find your way out in (zero-vis situation) with the oxygen supply in your lungs (may not be able to wait until the silt settles down).

Oh - you want protocol - I would say, UNassisted freediving only. Still, based on my limited knowledge, I do not believe freedivers would have the same buoyancy control that technical scubies would have to safely minimize the probability of a silt-out.

There are also issues with flow/current. Some you have to swim against; some suck you in. THe latter would pose the greater risk, I think.

One other safety protocol might be to make all freedivers aware of the significant, additional risks of this type of diving. This sounds trivial, but I suggest it in the same spirit as those apnea sites who warn that the practices/activities described/discussed therein pose risks of injury and death.

One other thing might be to not try breathing from gas bubbles: this past summer, there was a near-fatal incident in which a teenager tried to breath from a bubble (left behind by ???) but it turned out not to be breathable gas...

If there truly are steps that freedivers can take to explore caves safely as well as to regulate such diving in such away as to discourage ill-prepared divers from attempting such dives, I would be for it. However, if there are not... I can't say I would endorse this, but I apologize, I know that is not what this thread is about. You might ask freedivers who dive wrecks. If they penetrate wrecks, they might have some techniques/tips they can share with you.

I aspire to dive caves... but on tanx... Sorry, I hope I didn't come across as a kill-joy.

Please keep safe and best cheers to you and everyone.