21. Lake Natron, Tanzania
Lake Natron is a striking yet perilous location, renowned for its highly alkaline waters with a pH level as high as 10.5. The caustic lake can burn skin and eyes, and most life cannot survive in its toxic embrace. Temperatures often soar, and the water’s salinity is extreme. Amazingly, flamingos have adapted to thrive here, nesting on isolated salt islands and feeding on algae that flourish in the harsh environment. For most other creatures, however, Lake Natron’s lethal waters are a barrier to survival.