Nine miles in length and 2,500 acres of freshwater, Lake Hopatcong offers outdoor enthusiasts many recreational opportunities. Lake Hopatcong is the largest lake in New Jersey and the most striking feature of Hopatcong State Park. Visitors can enjoy swimming, fishing, a large picnic area with grills, boat launch access onto Lake Hopatcong, volleyball and basketball courts, soccer field and playground equipment.  Consists of the park Day-Use-Area (DUA) in Landing, NJ (i.e., the main park) and the park Annex located in the Borough of Hopatcong (accessed via Veterans Field). The Annex has no facilities and is hiking (Lake Hopatcong Trail) and mountain biking only. From Memorial Day weekend to Labor Day, inclusive, daily entrance fees are charged per vehicle for the Day-Use-Area (main park) in Landing. There is no entry fee for the park Annex in the Borough of Hopatcong.

The Lake Hopatcong Historical Museum is located in the main park, although hours of operation vary from those of the State Park. Swimming is only permitted on State Park Service property in designated areas when lifeguards are on duty. Visit the swimming schedule page to stay up to date on when lifeguards will be on duty. A large playing field is available for soccer and other field activities. One full-size court and two half-courts are available for basketball as well two beach volleyball courts.