i go skimboarding all the time and one time i lost the key that goes into the fob with the buttons... the car still drives... i was also thrown into the pool once with the actual fob ... it still works because it has a rubber cover on the inside that sorrounds the chip. i know about the rubber covering for a fact because my dog got a hold of my key when he was a pup and destroyed it so i had to pop the buttons out and fix them and i saw the cover around the chip.

but now when i go skimboadring i carry the plastic key that belongs to the plastic fob (with no buttons.) if you lose this plastic key you cannot drive your car with the plastic replacement key.

if i were you i would leave the fob with the buttons at home and take the plastic replacement fob and key with me...and when you go into the water only take the key with you and leave the fob thingy in the car.