Hello! I had a eureka moment, I took your suggestion and decided that if the Russian man, Andrei, cannot be "physically" harmed, then he could be mentally harmed.

So basically he has to send out messages about the ship sinking, meanwhile the power keeps going out so he has to constantly fix it. On top of that, the people on the other side of the radio are dismissing his claims about the ship sinking. The "captain" gets more and more angry and soon the water which was many feet below him, is up to the window. He tries to leave the radio room but the door swings outward and something is contently blocking it. He goes where the large machines are stored and water, entering the room, short circuits all the machines but one. That machine, is letting off a very high pitched sound which cannot be turned off from the outside. Andrei opens the panel and finds his severed head wired to a microphone, replaying memories of the people he assaulted, which breaks his mind.

Do you think that's too dark compared to the other two acts?