Located between Yosemite National Park and the Nevada border is an ancient saline lake, named after the county in which it lies. Mono Lake, which was formed about three-quarters of a million years ago, has no outlets to the ocean. Consequently, the lake has a lot of salt build-up and is very alkaline. This has led to a unique ecosystem and rock formations called tufa. Unfortunately, the level of the lake has been steadily decreasing due to excessive water use in the region and is at risk of completely drying out.

Mono Lake, CA