I've always wanted to go. There are God-created "jacuzzis" (!!), areas of water that have jets naturally! At least that is what a travel show said years back. Celebrities go in by helicopter. Owned by the Havasupai tribe.
Havasu Falls, Havasupai Reservation, Grand Canyon National Park, Arizona, United States. I hiked down to these falls (11 miles from parking lot), and it was every bit worth it! You need to plan on camping out a few days. It's too much to do in a short period of time.