Lake Titicaca - some pre-Inca ruins have ben found below the surface, which, although aren't so deep, might be just as interesting as the existing ruins on land.

Cosmic Ray Mutated Critters could be living in on the border of Bolivia and Chile. This is where the world's highest lake is, a spot which receives more UV (and therefore cosmic) rays than anywhere else on Earth. A team of scientists are currently trekking there to take a first peek at what might live in the lake.