The Mountain Lake Site (Smithsonian trinomial: 21CO01) is an archaeological site in Mountain Lake Township, Minnesota, United States. It is a deeply stratified village site spanning the precontact era from the late Archaic to an Oneota occupation, with a particular concentration of Woodland period ceramics. The site is atop a hill that was formerly an island in a lake. The site was listed on the National Register of Historic Places in 1977 for its state significance in the theme of archaeology.