In reply to Garethza:
> You get bags/cases that can make your phone waterproof - no need for a specific phone
Been there, done that, squinted through the hazy plastic - too many times. Given that you can get a waterproof phone for little more than £100, why would you bother?
To the OP's original question - I'd guess something like 30% of phones available today have some degree of waterproofing, so the answer to your question really depends on "what other features do you want?" Cost? Battery capacity? Screen resolution? Pose value?