There is quite a lot of preparation and safety procedures still in development unfortunately. At the same time it is a very sublime, peaceful experience. You drop down 70 ft. cover the entire length of a 130 ft. vessel at deck level and surface. Current can be running within reasonable limits and it really isn't a big deal. You may do that a dozen times. The dives are usually short, about a minute to a minute and a half. As you're not kicking, there is minimal exertion and usually no need to push things at all. Far less than when doing normal finning in free diving. Still, if your power dies, you hit something, get tangled, , stay too long into blackout territory, do too many rapid repetitive dives and get a nasty Type II DCS hit, things can go wrong. I don't know anyone providing instruction in this at this point, maybe Martin Stepanek with FII. I've been using DPVs in one form or another for free diving since the late '70's. Doesn't make me immune to screwups hopefully just drops the odds a bit on a good day. I don't recommend it for all the normal reasons. It is an interesting variant of free diving.
Here's a quick one from the Jay Scutti from the same session. Looks like the viz. may have improved a small amount.
[vimeo]5930922[/vimeo]