Lake Tahoe, in the Sierra Nevada mountains of the US, is famous for its clear blue waters. With visibility extending up to 70 ...

One of the reasons for the lake's crystal-clear waters is the roughly 50 springs that emerge directly from the lakebed.

visibility can stretch over 70 metres - almost as clear as distilled water. And while that might sound like something out of a lab, this is very much a natural wonder. The lake is known as ...