The iPhone 6/6s Plus is a pretty decent smartphone for doing work and capturing great photos. You can’t take it with you underwater without a proper case though. The Watershot Pro Underwater Housing for iPhone 6 Plus can help. It comes with an interchangeable flat lens port, ergonomic hand grip, and a metal mounting plate. It is rated to a depth of 195ft.
Watershot Pro comes with conductive buttons, allowing you to use your phone when it is inside. It costs under $170.