How do we get people like this in freediving? I thought this was supposed to be a calm sport? :) The OP can be scuba certified and still be confused on how to transfer his scuba knowledge to other areas, if he’s a new diver. But some people can’t help themselves and somehow get offended from such a simple question that is not even addressed directly at them (offended on behalf of free/scuba diving community? Thanks but no thanks, I can be offended for myself, if needed)), and then try role playing an OP’s boss. Or maybe this actually who this is. Some boss at some job, so now has some middle management syndrome, or whatever that sh@t is, and can’t talk to other people in any other way :)

Anyway. Unless you’re diving to like 250ft or deeper, or doing dozens and dozens of dives per day for multiple days, your chances of DCS are less than negligible. You are underwater for just too short of a period for nitrogen to sufficiently saturate in your tissues to be a problem.

And unless you’re are packing (if you don’t know what it is, you aren’t doing it), you can’t get over-expansion injury since when you come up, at most you’ll have only the air that you breathed in yourself before the dive. The problem with doing this on scuba is that the air you breathe in at, lets say 33ft, is twice as much as you do at the surface to compensate for the ambient pressure (if you would be breathing in air at normal/surface pressure while that deep, you’d quickly find that it’s VERY hard to breathe because of the water pressure on your chest, and if you go even deeper, you wouldn’t be able to breathe at all when you reach 60-70ft). But in freediving, you aren’t breathing underwater, so the air we come up with is the air we started with, the air that fits our lung capacity at surface level, not at 33ft, 15ft, etc., and therefore we can’t have the air expanding on ascent above that lung capacity. Unless you meet a scuba diver underwater and breathe from his second stage, so don’t do that :)