Why couldn't you drink salt water?

Answer 1

Well, you could drink salt water if you wanted to. But drinking too much salt water can be deadly. What happens is the salt in the water draws water out of your cells. That's why your skin feels dry when you come out of the ocean. So if you put that salty water into your body, the same thing happens, but internally.

In short, drinking salt water is actually dehydrating yourself.