alcoholic drinks with an alcohol content of less than 4 per cent, such as light beer and lager, can be used to stave off dehydration.
Seawater, on the other hand, is an emetic, so, if you drink it, you’ll throw up. If you do manage to keep any of it down, then all the water in your body’s cells will move towards the highly concentrated salty fluid, by osmosis, in an attempt to dilute it.
This will leave your cells dehydrated, and in severe cases can lead to spasms, the breakdown of brain functions, and liver and kidney failure