Kayaking
While not as good as at Phang Nga, the kayaking around the peninsula at Rai Leh affords a great alternative to climbing and a stunning view of the area. Several of the limestone islets off Phra Nang Beach have sea caves eroded into their bases, including a few large enough to offer opportunities to beach the kayaks and explore. Paddling into caves and through subterranean passages is particularly interesting, but watch out for low, jagged ceilings. For those with more ambition, a short open-water crossing (about one hour of steady, heavy paddling) leads to the private island of Ko Poda which has beautiful and relatively isolated beaches.