Round Valley Recreation Area sits in the rolling hills of Hunterdon County, straddling Clinton and Lebanon Townships in central New Jersey. Established in 1968, this state park centers on the 2,350-acre Round Valley Reservoir—a deep, spring-fed lake carved into the surrounding highlands that offers some of the clearest water in the state.

What makes Round Valley stand out is the reservoir itself. With depths reaching 180 feet, it’s one of New Jersey’s deepest bodies of water and a destination for scuba divers exploring submerged structures and dramatic underwater drop-offs. The lake draws anglers chasing trophy lake trout and brown trout, species rarely found elsewhere in the state. Swimming is popular at the designated beach area, where the clean, cold water provides genuine relief on summer days.

Hiking and mountain biking trails loop through the wooded ridgelines surrounding the reservoir, offering elevated views of the water and the Cushetunk Mountain ridge. The 9-mile Cushetunk Trail traces the full perimeter and rewards with quiet stretches away from the main recreation areas. Boating—both motorized and non-motorized—is permitted, and the reservoir’s size means you can find genuine solitude on the water even on busy weekends.

Round Valley offers wilderness camping accessible only by foot or boat, making it one of the few backcountry camping experiences available in New Jersey. Sites sit along the southern shore, well removed from roads and crowds.

Visit from late spring through early fall for swimming and camping. Fall foliage along the ridge trails is particularly striking.

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