Fathoms Below (слэш)

A pissed-off merman sinks Tony’s ship while Tony’s still inside, trapping him at the bottom of the ocean. Now, Tony’s life depends on the rapidly shrinking air pocket he’s using to breathe.
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Tony doesn’t want to die.
He scrubs wet hands up and down his face, unable to stop shaking.
Maybe it isn’t over yet. Maybe he can do this. He’s survived bad odds before, he can survive this too. He just has to stay calm and try to think. He can’t bring air with him. That’s fine. Maybe he can generate air on the go. Throw together a makeshift electrolyzer and pull oxygen from the water, or… or… or jerry-rig a pressurized suit he can wear to the surface to keep his nitrogen dissolved in his bloodstream until help arrives. He has options, he must have.
He just has to keep trying and think.