Lake Mead

 is a lake in the Mojave Wasteland. It has pure water, so you can drink it and fill up your H2O meter. The area is crawling with lakelurks, so going there to fill up your H2O meter will be no walk in the park.

There are also (at least) two apparent easter eggs located in the depths of the lake, including an underwater cave and a crashed airplane which appears to be a reference to an actual airplane crash that happened in Lake Mead (http://www.eculturalresources.com/news/756.html)

Appearances
appears in Fallout: New Vegas.