The ghastly Lake Natron, in northern Tanzania, is a salt lake—meaning that water flows in, but doesn’t flow out, so it can only escape by evaporation. Over time, as water evaporates, it leaves behind high concentrations of salt and other minerals, like at the Dead Sea and Utah’s Great Salt Lake.
Unlike those other lakes, though, Lake Natron is extremely alkaline, due to high amounts of the chemical natron (a mix of sodium carbonate and baking soda) in the water. The water’s pH has been measured as high as 10.5—nearly as high as ammonia. “It’s so high that it would strip the ink off my Kodak film boxes within a few seconds,” Brandt says.