Khao Kob Cave in Trang is popular with Thai. In order to visit you need to hire a little boat and guides (it’s 200 baht). My boyfriend and I got our own boat just because everyone else was in a group and there was no one to share. No problem. That let me look around the cave. You start out going down a little klong (baby river) that eventually reaches a rock face. That’s when you are told to lay back and things get a little more