From the intersection of State Hwy. 78 two miles, then north on Beich Road 0.75 mile, then west on the access road to a parking lot. Lost Lake is perched near the upper end of a ravine that is about 0.2 mile wide and 0.5 mile long and drains to the northwest. The vegetation association of yellow birch, mountain maple, alder, black ash, green ash, hackberry, poison sumac, and sphagnum moss that surrounds the lake is unusual. The forest on the slopes flanking the hollow grades into a red oak, basswood, yellow birch, hackberry, and white ash forest.
White oak becomes predominant further upslope.
The northeast side of the hollow has a low cliff with an exposure of quartzite conglomerate with layers of sandstone found nearby. The southwest side of the hollow is partially bounded by a cliff composed of quartzite blocks. The water is light brown and has an alkalinity of 139 ppm and a pH of 7.3. The lake's maximum depth is 17 feet. Wildlife includes snapping turtle, green and gray tree frogs, green-backed heron, and Louisiana waterthrush.