The Debunker: Can a Little Bit of Seawater Stave Off Thirst?

by Ken Jennings

June is the time of year the United Nations observes World Oceans Day and the U.S. celebrates National Oceans Month, so we’ve asked Skipper Ken Jennings to navigate us through four maritime myths that refuse to die. It turns out that none of them really hold water.

Ocean Myth #4: Stranded at Sea, You Should Drink Seawater in Small Quantities.

In 1952, a French biologist named Alain Bombard decided to cross the Atlantic Ocean in a small inflatable boat almost entirely without provisions. He hoped to test theories and discover techniques that could one day save the lives of other unfortunates finding themselves, as it were, in the same boat. In particular, Bombard believed that drinking seawater could sustain life, as long as the drinker wasn’t already too dehydrated, and could limit his intake to less than a pint and a half a day.

Bombard survived the journey, though not without misadventures, and as a result of his account (and those of other ocean castaways unable to resist the “water, water everywhere” surrounding their craft) it became conventional wisdom that the lost-at-sea could prolong their lives on small quantities of seawater. For a time, some Navy and Air Force survival manuals even included this advice.

But it’s terrible advice, potentially fatally so. Seawater is about three times more saline than human blood, which means that body is going to have to get rid of that extra salt somehow to keep functioning. The mechanism to do that: urination, which has the unfortunate side effect of dehydrating you even more and making you want more seawater. It’s a vicious circle, which soon leads to diarrhea, seizures, brain damage, and finally kidney failure and death. So how did Bombard and other ocean-drinkers survive? A German doctor named Hannes Lindemann, who tried to duplicate Bombard’s journey, decided that Bombard must have supplemented his saltwater regimen with secret reserves of freshwater. Whether or not that’s true, Bombard’s seawater diet may not have killed him, but it certainly wasn’t keeping him hydrated. Castaways who survive while drinking seawater would have survived anyway—and probably with their kidneys in better shape. Besides, to paraphrase W. C. Fields: “Fish poop in it.”

Quick Quiz: The recently reunited rock band Veruca Salt is named after a character from what book?

Ken Jennings is the author of Because I Said So!, Brainiac, Ken Jennings's Trivia Almanac, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.