Question

If you were stranded in the ocean, why would drinking sea water not be advisable?

Answer 1

There is a ton of salt and water so you are drinking too much salt and too much salt is bad for the body.

Answer 2

Sea water, also called salt water, has a high concentration of sodium that causes you to actually loose hydration, so while you are consuming liquid, your body feels more dehydrated from the salts leeching the water from your body. This would make a bad situation worse if you are stranded in the ocean, as you would need to conserve all the fresh water you can and keep as hydrated as possible.