Well survival at sea is a big thing. It has been since the first boat sank. When your stranded and in the ocean you need to know hot survive or you will die a very bad death.
Well their many ways have probably get yourself in this kinda situation. Your may have had ditch airplane or jump out of it with parachute, or ship sank is now with Davey Jones.
Remember stay hydrated but never drink the salt water cause you can die, re,her drink fresh water only.
Find food food is all around in the ocean but you might have some food that survived on your got yourself in the situation.
Being attacked by a shark well you have get yourself out if this of you will be going up the creek without a paddle. Well there are weak spots the snot and the eyes eyes ar highly recommended. Don't play dead ever cause they will just eat you then of course. If you got a gun shot,revolver, pistol, rifle msg and assault rifle those are probably going to work above water, under water guns (not squirt guns) will work too. If you have limb bitten on by shark latch too it, less chance of limb being ripped off drop the gun if you have one do not wanna lose that.
Did you know you can live off of seaweed but you should boil it first.
Well of you want your have the best chance of getting seen by the plane is actually night cause those flares will light up the sky and the plane will look for you.