First, I'd probably have Céline Dion's "My Heart Will Go On" in my head then hopefully I would snap out of it and try and find a life jacket, raft or life buoy. Will help any others before it submerges.
'If only I bothered to learn how to swim.......'
I would sit on a survivor's head and use them as a liferaft
Find a hole and just keep swimming swimming swimming
Let myself sink.
I would rip floarboards off the ship and ducktape them together to make a single person sized replica of the sainta maria, and sail to safty.