If stranded on a deserted island with no freshwater it is not advisable to drink sea water. Why not?

Drinking seawater is not advisable because it contains high levels of salt, which can lead to dehydration. When you ingest seawater, your body needs to use more water to excrete the excess salt, ultimately worsening your dehydration. Additionally, the kidneys struggle to filter out the salt, which can lead to further health complications. In a survival situation, it's crucial to find alternative sources of freshwater instead.