From NJ fish and wildlife;
The legendary "blue hole" at Winslow WMA is a circular pool of water about fifteen feet wide. Created by a spring that no longer flows, the water is crystal clear to depths of almost twelve feet. The legend is that the water is ice cold and bottomless, and a home of the Jersey Devil. To reach the blue hole, Turn Left onto the first sand road off of Piney Hollow Road, 0.7 miles from Rt. 322. Continue a short way through the woods to a small parking lot with a "shooting range closed" sign. From here, hike the first trail to the right - you will pass through bogs of blueberry and cranberry and arrive at a clearing with the famed pond. The hike is less than 1 mile total. It is not advised in wet weather as the sandy trail will be mostly underwater.
Weird NJ said 9’, Fish and game says 12’ I guess we still need to map and dive this to set the record straight, any reason for an exploratory dive :)