We’ve all heard of the Dead Sea, so salty that people naturally float in it. But the Gaet’ale Pond in Ethiopia is saltier, and the Don Juan Pond in Antarctica is so salty that it doesn’t freeze, even at -50°C.
There’s a particular class of lakes and ponds called hypersaline lakes because they have a salinity level much higher than most bodies of water. Many are located in deserts. They’re often at the centre of an endorheic basin: water drains in but it does not drain out. Instead, the water evaporates and the salts are left behind. Sometimes, salt is added by geothermal processes.
Everyone knows about the Dead Sea’s hypersalinity. But there are other, saltier, bodies of water out there. Their exact relative salinity is ambiguous (seriously, the Wikipedia articles contradict each other about just which is the most salty) but two super-salty ponds are worth your attention.
The Gaet’ale Pond didn’t exist until 2005. An earthquake opened up a thermal spring and the pond appeared. It’s about 60 metres across, and it’s possibly the saltiest pond in the world. Noxious gases bubble up to the surface, so it may be one of the more dangerous ponds in the world as well.
Don Juan Pond is a body of water in Antarctica. Most of Antarctica is frozen, of course, but this little pond – 300 metres wide and 100 metres long – is trapped between a river and a rock glacier and so is super-salty. As a general rule, the saltier water is the colder it has to be to freeze it (ocean water freezes at around -1.8°C). Don Juan Pond apparently stays liquid at a ridiculous -50°C.
About that name, by the way: Don Juan Pond is named for the two helicopter pilots who discovered it, Don and John. Bunch of jokers, these Antarctic helicopter pilots. It’s hardly the corniest name in Antarctica: Don Juan Pond abuts the Asgard Range.