It's about a man who murders women and puts them underwater as art. I can't remember much else but it was probably made in the late 90's or early 2000's.

Could be Cabin by the Lake.

Possibly The Cell (2000) (http://www.imdb.com/title/tt0209958/)
Or In Dreams (1999) (http://www.imdb.com/title/tt0120710/)