It is best if you have a therapist with you, or at least ready to receive a phone call?

Flooding is a type of desensitization in that if you do it over and over, supposedly you will become callous to it and it won't bother you any more. But this needs some expert guidance because for some it can retraumatize you.

The idea of being held under water is not an easy thing to work through. Not only are you trying not to suffocate, and feeling some claustrophobia, but you also have the problem with someone having control over you. That's a lot different than say figuring out if an elevator is safe enough to ride a floor or two.