The Consequences of Drinking Sea Water
Sea water on average is about 96.5% water, and is approximately 3.5% salt. The amount of salt can vary, more or less, in amounts of 3.1 to 3.8% depending on location.
Because of the relatively enormous amount of salt in sea water, individuals who drink it will be subject to dehydration if they partake of it in copious amounts but do not offset it by ingesting fresh water. The high salt content removes moisture from your body through the process of osmosis. This dehydration may cause seizures, unconsciousness, mouth ulcers, swelling of the limbs, brain damage, kidney damage, and ultimately death.
Some of our studies of drinking sea water come from the Nazis. Adolf Hitler despised Gypsies, and tried to exterminate them. At Dachau, his henchman Dr. Hans Eppiner took a group of 90 Gypsies and forced them to drink only saltwater. The Gypsies were so dehydrated that they took to licking freshly mopped floors in a desperate quest to obtain potable water. Many became ill, and some died.
And of course movie lore is fraught with tales of shipwrecked people who succumbed to drinking sea water, and then went insane as a result.