Triathlon Training Watch

I'm thinking about buying a watch for using while I train. Are there watches out there that can track swim distance in open water? Not by the looks of it, not unless you want a laptop on your wrist in the form of the Garmin 910xt, It just seems huge. Somebody tell me if I'm wrong. I looked at the polar rc3GPS but it is not water resistant enough for swimming. The only thing I can think of is to buy the Polar rcx3 (as it is waterproof) and use it with the GPS device under my swim cap. I'll let you know if it works when the water warms up.