Turtle Island, also known as Guishandao, is Taiwan's only active volcano and a must-visit destination for nature lovers. Located off the coast of Yilan County, this uninhabited island offers stunning views of the surrounding Yuanyang Sea, where cold seawater mixes with hot spring waters to create a unique milky blue color. Visitors can explore the island's various attractions, including the Turtle Tail viewpoint, the 401 Peak with its watchtower, and the old village with its stone houses. To visit Turtle Island, it is recommended to book a tour in advance, which includes a boat ride and a special island landing permit.