[maratc]

I'm one training short of hypoxic trimix (after a regular trimix course). I think you seriously over-estimate the complexity: open-water course is 3 days, advanced open-water is 2 days, nitrox is ... half a day?, basic tech diving (advanced nitrox + decompression procedures) is 7 days (50-100 dives minimum iirc), trimix is another 7 to 10 days.

Loads of people I know did all that without any difficulty and without leaving their day job. They weren't in the navy either.

The most advanced thing that I see here is how do you trigger the explosion underwater, plus of course getting the explosives somewhere.

[semi-extrinsic]

Yeah, maybe I am over-estimating, I only have advanced open-water. But I thought you had to have logged like 50 dives at X depth between each step up the training ladder for trimix, so you need a minimum of like 200 dives total to reach hypoxic trimix? In my book that is multiple years of practice and not everyone will cut it.

So an organization either needs to make preparations for this many years in advance, or try to recruit someone who both has some form of extremist beliefs and a hobby that requires very specialized training. Neither of those things are very simple, but the first one is doable, yes.