They are waterproof. You will need them to get into the pool area at the resort, so I would leave them on while you are swimming. Just be sure they are still on your wrist when you leave the pool area, as we found one at the bottom of the pool. As far as in the room, showering, etc., we did not leave them on at night or while we were in the room. The only thing to be careful about is forgetting them in the morning (or any other time we left the room). DH always goes down to CS to grab breakfast for everyone and coffee. Because he hasn't had his coffee, he forgot his MB about every morning and couldn't get back into the room without DD or I opening the door for him.