This 296-acre (1.20 km2) barrier beach park offers lifeguard-supervised swimming, sunbathing, fishing, scuba diving, and special events.

A food concession, restrooms, a first aid center (staffed by an EMT during the summer months), showers and changing rooms are all situated at Cupsogue's pavilion.

Diving is permitted at slack tide on the bay side of the park only, where the water depth is approximately 12 feet (3.7 m).

The park's land was entirely part of Fire Island until a 1931 Nor'easter created the Moriches Inlet, which enlarged between 1933 and 1938.

A breach connecting the Atlantic Ocean and Great South Bay occurred on the east end of the park as a result of high tides during Hurricane Sandy in 2012.