There aren't too many options for freshwater diving around here. That's not to say that you can't try jumping into any body of water you find, but most of them are likely to be pretty awful, and a few could get you arrested. Two good freshwater dives in the region are Round Valley Reservoir and the Delaware River Water Gap. Some diving is also done in Lake Hopatcong, although access is a problem.
Sadly, 2021 is Dutch Springs' final year of operation. The owner has retired after 40+ years of building and running the facility, and the property has been sold to a developer to become warehouses. See the link in the sidebar.
lakehydra.com
Dutch Springs contains many interesting artificial reefs for divers to explore. In fact, even the hole itself is man-made - it is an old limestone quarry.
Looking roughly southeast, with the diving cove in the foreground. The natural basin of the valley is evident, as well as one of the two dams, at right. The water level looks pretty high, with a little snow on the ground.