My only concern with the waterbouy is the first one i had went off by accident and soon deflated as it had a small pin hole in the top of the ballon
. The company sent another one out free of charge and stated that the new models are less likely to go off by accident.
I have just bought one of these for my phones having seen a chap with one today on his rib. Boxit - Built For Action
Waterproof, shockproof and floats.