I can't speak from experience because my son loves the water, but maybe if you try putting some toys in the tub with no water - just let him play with his toys, fully dressed for a while. Or if you have a water table, and are really brave, maybe you could bring that into the house (put a blanket underneath or something) and let him pour water from a cup in there, and maybe try 'blowing bubbles' in the water and see if he'll copy you. Most importantly though, try to remain as calm as possible during his theatrics. If he senses for one second that you're agitated, or if your comforting actually validates his fears, he may become more hysterical. There are probably fun dvds out there too, showing Elmo taking a bath or something. Or, this may sound strange but he's young enough that this wouldn't be inappropriate, what about a playdate that included a shared bathtime? If you have a friend or relative with a little one, maybe you two could give the kids a bath together. Maybe having another kid in there with him will make it seem more like fun and less frightening. Whatever you do, good luck, and remember that they eventually grow out of everything.