You know how eating salty food makes you feel thirsty? Understanding why you should never drink water from the ocean or sea, especially in survival situations, is easy when you keep this scenario in mind.
Sea water, ocean water, and salty food are all similar because they have high concentrations of salt. Although the human body does need some salt in order to stay healthy, too much is dangerous for you. When you ingest high levels of salt, by drinking seawater or eating salty food, your body tries to expel what salt it doesn’t need so that it can keep you healthy.
Most of the time, this is no problem. Your body’s way of flushing out toxins and correcting the imbalances in your system is through expelling these excesses in your urine. In order to get rid of more toxins or excesses, all your body needs is more water. The sensation of thirst is your body’s way of telling you it needs that water. Of course, sitting at home eating a bag of chips, this is easy to fix: fill a glass and drink, and you’ll be good to go. But when you’re lost in the middle of the wilderness where suitable water is hard to come by, becoming too thirsty can ultimately mean dehydration.
When you drink salty water, from the sea or the ocean, you’re putting both salt and water into your system. The problem is that the amount of water you take in is nowhere near the amount you’ll need to expel the salt, and if you keep drinking the seawater, you’ll keep adding to the amount of salt you need to get out of your body. When you drink water from the sea or ocean, your body needs more water to get rid of the salt than it’s getting out of the seawater itself. Essentially, when you drink seawater, you’re dehydrating yourself.
That’s why after drinking seawater, you’ll become more thirsty than you were before: because you’re causing your body to need even more water than before you drank the saltwater.
To sustainably drink water from the ocean or sea, you’ll need to get rid of all that salt first. While this is possible to do, it’s not a particularly easy task, especially in survival situations.
All this to say, do not drink seawater as it stands. It will always make you worse off than if you had never drank it at all. Drinking seawater when you’re dying of thirst will only make you die of thirst faster.
P.S.: If you’re thinking you can drink just a little seawater at a time to keep yourself from becoming dehydrated, and you’re basing this on your discovery of Alain Bombard and his writings, please take the time to read my follow-up article to this post: “Can I Drink Small Amounts of Seawater in Survival Situations?”