Beach Beach Introduction: The Guanyin Reef Bathing Beach on Damen Island is the second largest beach on Dongtou Island. The water is clear and the sand is fine. It is a good place for swimming and beach sports. The sand at Ma'aotan Bathing Beach, another one on the island, is iron sand, which is fine and pure but not loose. It is very comfortable to step on. It is the largest beach in the Dongtou Islands.