Near Ao Phra Nang, geology buffs should head to Susaan Hoi (the fossil shell cemetery), where strange dark sheets similar in appearance to fragments of tarmac litter the bottom of a cliff. As you approach along the path descending to the beach, fossil beds, made up of shells 75 million years old, come into view. This extraordinary geological site is one of just three of its kind found around the world (the other two are in Japan and the United States).