What are the most intense professions that you can think of?

A marine engineer? Not special operations or even infantry?

@Invisible: I'm talking about the ones living onboard ships and submarines.
Depending on where they are, the temperatures they are working at can be in excess of 110-115 F/ 45 C. All the time.

Navy work is on the other side of the spectrum; they freeze their asses off lol. I'll take the heat over the cold, personally!

@Invisible: Naaa man. I've been there. I'm talking from personal experience. The heat is unbearable !! It can go up to 50-54 C inside the engine room, in the middle east areas. I'd prefer the cold over the heat any day !