Since the west-side of the island is mostly inaccessible by road (car rental agencies will specifically tell you not to drive there), we all went on a boat trip to that side the day before the wedding.
The trip starts in Adamas and goes around the west coast, stopping at very beach on the way, until Kleftiko Bay, where they served us lunch (or a meal if you don't agree that food at 16h counts as lunch). Then we went back to Adamas just in time for the sunset.
They have equipment for snorkeling, although there's not much to see, just some cute fish here and there, and they'll take underwater photos for you. There's plenty of boats on the port that do this route, just ask around for prices :)