The lake is approximately long (north-south) and from wide (east-west), covering , with a maximum depth of . It contains eleven islands (Loon Island, Elizabeth Island, Twin Islands, Great Island, Minute Island, Little Island, Star Island, Emerald Island, Isle of Pines and Penny Island) and is indented by several peninsulas and lake fingers, a combination which yields a total shoreline of some . There are seven sandy beach areas including Mount Sunapee State Park beach; some with restricted town access. There are six boat ramps to access the lake at Sunapee Harbor, Georges Mills, Newbury, Mount Sunapee State Park, Burkehaven Marina, and a private marina. The lake contains three lighthouses on the National Register of Historic Places. The driving distance around the lake is with many miles of lake water view. The lake is above sea level.