I listened to John Barry's Theme from the Deep for inspiration. dan@bigwinky.com

Other credits: Bubbling scuba sounds: https://freesound.org/people/carmsie/sounds/329915/ uploaded by Carmsie who inturn credits: 274491__timsc__under-water-sounds-while-scuba-diving 147187__hampusnoren__under-water-bubbling 147182__hampusnoren__under-water-splash-7

Image by johnallds from Pixabay