Hanging Lake is a suspended lake high above Glenwood Canyon in western Colorado, formed when part of a valley floor sheared away along a fault and dropped to create a shallow lakebed. Fragile travertine built up around its shore as dissolved limestone was redeposited, and carbonate minerals give the water its turquoise color. The area passed from local lore and private retreat to public ownership after the Taylor Bill in 1910, later becoming a major tourist destination. Returned to Forest Service protection in 1972 and named a National Natural Landmark in 2011, it now draws heavy visitation under strict permit-based management to protect its sensitive ecosystem.