Foul Rift is a Class II rapids in the Delaware River from mile 196.3 to 196.7, located about a mile south of Belvidere, New Jersey. The rapids are caused by a 22-foot descent in elevation of the limestone ledge riverbed for approximately 0.5 miles, and are considered to be the most dangerous on the Delaware River.[1] At elevated water levels some of the narrower rapids can become extremely dangerous.