I am over the idea of babying my Garmin 305... and plan to try freshwater swims with it... I'll probably put a small piece of duct tape over the battery on the strap and the contacts on the watch, and see what happens.

I would not advise this for salt water and it's overkill for the pool (I have used my old polar when so inclined) so once the temps warm I'll give it a go.