Find the volume of solid , how many galons of water are need to fill the pool?

The diving pool at the Aquatic Center was used for the springboard and platform diving competions of the 1996 Olypic Games. The pool is 78feet long and 17 feet deep, and it is 110.3feet from one corner on the surface of the pool to the opposite corner on the suface . If it take 7.5 gallons of water to fill one cubic foot of space, approximately how many galons of water are need to fill the pool?