Subject: Re: submersible
Yeah, if there was an actual breach, they're dead. At that depth, a leak will be like a cutting jet ripping through anything soft it encountered. More likely would be a sudden implosion, which would be quick. They wouldn't have the time to drown.

If it was loss of power, or something similar, that is less merciful. They will get cold, and may expire from hypothermia before they would asphyxiate. I agree it is comparable to being in space.