Shark Repellent Wristband: You survived a ship going down. It would totally not be cool to get eaten by a shark while adrift.
Waterproof Goggles: To keep the salt water out of your eyes and any oil floating on the surface from the ship.
Survival Bag: These are made specifically for abandoning ship. Waterproof with lots of pockets and tethers inside to keep your gear together and ready.
Portable Phone Charger: With no ship and no power, your phone will need some juice. A powered up portable charger in a waterproof container is a must.