On the east coast of the island of Sal, in the crater of an extinct volcano, you can float in a lake with water over 20 times saltier than the sea.
Pedra de Lume is famous for its salt evaporation ponds, which have been used to produce salt for nearly two centuries. You can see old cable car structures that were built in the 1920s to transport salt to the nearby port. Salt production has slowed here, but it is still produced today in small quantities.
It sits in the middle of a volcanic crater. The edge of the crater is its highest point, at 39 meters above sea level. Down in the middle of the crater, the elevation is far below sea level. The lake formed naturally, fed by underground water sources.
The salt is said to have health benefits, and you can also cover yourself in therapeutic mud.