Drinking seawater or any kind of salt water increases the salinity of the blood. That actually draws water out of the cells, which ultimately shrivel and die, and the person drinking the water can die of dehydration. The mechanism responsible for this is osmosis.

Can you die from drinking seawater?

Additionally, when we consume salt as part of our daily diets, we also drink liquids, which help to dilute the salt and keep it at a healthy level. Living cells do depend on sodium chloride (salt) to maintain the body's chemical balances and reactions; however, too much sodium can be deadly.

Why would drinking salt water kill you?

Why Too Much Salt Is Deadly

When too much salt enters the body it disrupts your ability to naturally regulate the amount of water in your cells. A high concentration of salt can make the water content in a cell appear higher than it actually is, causing the water to leave the cell and enter the bloodstream.