Well i have a mild form of acrophobia i think, probably could be more described as mild vertigo. I have always swerved the opportunities to skydive, parachuting, abseiling, bungee jumping anything like that, dont really even like looking over the edge of really tall buildings. Also one of my greatest fears is drowning so neither appeals to me! But if i had to pick it would be breathing underwater because i wouldnt have to worry about drowning, although the claustrophobia of water all around me would have to be got round. But with flying the fear of being high would always be there, so breathing underwater it is.