It rained like hell on lingerie night during our first trip. They kept the music going at patty-o's, so we kept drinking, dancing and eating burgers. Awesome time and one of our best memories!
We always upgrade to the Jacuzzi rooms. We move the party to there. And depending on the time of the year, it can even get a little cool when the rain comes. We just get a group, together, tilt the TV so you can see it from the deck, warm up the tub and hang out there. If you get a close near the quiet pool bar and you tip well they will even deliver drinks
If it's raining go snorkeling you're gonna get wet anyway. Go check out the statues or if you want to be dry see the exhibit at the Kuklakan Mall. https://www.google.com/search?q=und...VzYGICg&ved=0CC4QsAQ&biw=1517&bih=741&dpr=0.9