Lake Willoughby is a glacial lake over 300 feet (91 meters) deep in places, the deepest lake entirely contained in the state. The southern end is surrounded by the Willoughby State Forest. This state park includes Mount Pisgah, Mount Hor, and Bartlett Mountain.
Willoughby is listed as a National Natural Landmark. A fisherman caught the world's largest lake trout, 39 pounds, ever caught through the ice. Willoughby contains rainbow trout (wild & stocked), landlocked Atlantic salmon (mainly stocked), rainbow smelt, burbot, yellow perch, longnose sucker, white sucker, lake chub, common shiner, and round whitefish which is a natice species of extremely limited distribution in Vermont.
The sheer cliffs of Mount Pisgah and Mount Hor provide an environment conducive for arctic and cliff-alpine plants, as well as ideal nesting areas for the rare peregrine falcon.
More than 100 bird species has been recorded around the lake including thrushes, warblers, hummingbirds, jays, finches, loons, herons and gulls.
