You know, a chainmail shark suit is something which might actually be realistic to find in a dive shop along with swim fins, oxygen tanks, spearguns, et al.[/quote]
There’s a PR in the hopper for one, but it’s missing spawns. 
Update to respond to Coolthulhu:
[quote=“Coolthulhu”](Sorry for doublepost, but those are separate things)
So no to production of itemized hydrogen, but would it be OK if there was a way to produce and feed hydrogen directly to tanks? I wanted to make an electrolysis car part (to add a useful, if highly wasteful, energy sink).
I see no non-cheaty way of siphoning hydrogen out of a tank.
The cheaty way involves destroying a loaded hydrogen tank using acid or something like that. The result is not only extra item hydrogen, but 100 times more of it than was put into the tank.[/quote]
And I’m sure something would spark, somewhere. At which point maybe we can dial back gas-tank explosions.