Complex sentence: Monksville is a very small town under water in the middle of Monksville Reservoir in Passaic County, New Jersey that Jacques-Yves Cousteau once visited and filmed in a submarine.
Split into simpler sentences: Monksville is a very small village, today located under water in the middle of Monksville Reservoir in Passaic County, New Jersey. It is purported that Jacques-Yves Cousteau once visited and filmed the underwater town in a submarine.