Round Valley Recreation Area is a shore accessible fresh water dive site, located at 1220 Lebanon-Stanton Road, Lebanon, NJ 08833-3115. This dive site has an average rating of 2.89 out of 5 from 9 scuba divers. The maximum depth is over 150ft/46m. Training platforms are available.
The brisk blue waters of Round Valley Reservoir attract swimmers, boaters, fishermen, picnickers and campers to its scenic shore. The Round Valley Reservoir swimming area was created by the construction of an earth dam across a narrow waterway on the west side of the reservoir, separating it from the main part of the reservoir. The reservoir covers over 2,000 acres and is approximately 180 feet deep, the deepest lake in New Jersey. It has a water capacity of 55 billion gallons. The reservoir is stocked with lake trout.
More info
http://njscuba.net/sites/site_freshwater.html