Waterproof tape/wrap/sleeve for foot injury

I am a surfer and have the beginnings of a 'surfer's knot' on one of my feet from the constant banging/rubbing/pressure on the hard surface of the board. It's a pretty common condition in surfing:
surfer's knots - Encyclopedia of Surfing
Just a moment...
I'm not looking for medical advice as I've already been to both podiatrist and an orthopedist and was told all I need to do is to pad the area. The challenge is that I need something that can go on the ball of my foot that will stay on in the water. Does anyone know of a tape/wrap/ace bandage that will stay in place in water?