Lookout Mountain is a one-thousand-one-hundred-sixty-five-foot summit in the Borough of Hopatcong, Sussex County, New Jersey, overlooking the River Styx, a bay of Lake Hopatcong. Rather than standing apart as an isolated peak, it rises directly above one of the lake’s inlets, linking it closely to the surrounding waterscape. The mountain is part of the New York–New Jersey Highlands, a long band of rocky uplands that extends through northern New Jersey into New York within the larger Appalachian Mountains, giving the summit both a local identity tied to Lake Hopatcong and a broader place in the Appalachian highlands.