The town is the original set from Little House on the Prairie (1974). In the exterior escape scene, you can briefly see the famous hill where Laura, Mary, and Carrie Ingalls run down.
The exterior forest and river scene is the "backyard" for the famous JPL (Jet Propulsion Laboratory) in Pasadena, California.
The underwater scenes were filmed at the famous Rose Bowl Aquatic Center while the USC girls diving team practiced at the other end.