swimming in the ocean

I had a dream last night that I was swimming in the middle of the ocean.  I had something to keep me floating but I don't know what it was.  A ship came near but I ignored at.  It felt like this had happened before and the ships had never noticed me and I was okay with that.  This time though someone on the ship did notice me and jump off and swam after me.  He started talk to me and I told him to leave me alone.  He was swimming toward and I tried to swim away but I was afraid that I would loose whatever was helping me float.  He got closer and closer and just when he was about to grab me, I woke up.