Sansiantai is a promontory that separated from the coast by sea erosion. The geology here is composed of volcanic agglomerates from Duluan Mountain. The surrounding water is a magnet for fish, making this a popular diving and angling spot. The name, which means "Three Immortals Terrace," is a reference to three large boulders here, said to represent the celestials Lu Tung-pin, He Sian-ku and Li Tie-kuai.