Christophe, your character would likely have been caught up in cranes, cables, falling chairs, and people. A rush of seawater invading the superstructure would likely pull him into the ship or against it, releasing him only when he was deep below the surface and some pressure equalized. I'd say, a dead man in this case.
I heard a saying that when bodies was forced to certain depth, their buoyancy lost and could not therefore float again. May it be a clue that only three hundred bodies were found but not another 1200. That is one of the most horrible way of depth. See the scene of Titanic (1997) slowly and carefully when Jack and Rose were dragged underwater. There are also some people dragged underwater. I often wonder that they survived to the surface (although they were most likely frozen to death even they made it)