Sanxiantai, located in the northeast of Chenggong Town, Taitung County, is composed of small offshore islands and coral reefs. The island is dotted with strange rocks, including three huge rocks. Legend has it that Lu Dongbin, Li Tieguai, and He Xiangu once visited the island, hence the name. The geology of Sanxiantai Island belongs to the agglomerated rocks of Duluan Mountain. It was originally a headland, but the neck of the headland was gradually broken due to seawater erosion, and it became an offshore island. In the past, tourists who wanted to visit Sanxiantai could only use the low tide to wade across the water. In 1987, the eight-arch sea-crossing bridge was completed. Its wave shape is like a giant dragon lying on the sea, connecting Sanxiantai and the main island. A very famous landmark on the east coast. The island is surrounded by coral reefs. Due to strong weathering and sea erosion, in addition to the natural wonders related to the story of Sanxiantai, such as Xianjian Gorge and Hehuan Cave, there are also sea erosion ditches, pot holes, sea pillars, and sea erosion concave walls on the island. Such as sea erosion landscape, visiting the island is full of interest in seeking seclusion and visiting victories. Sanxiantai, which is rich in ecological landscape, is an important base for studying coastal plant ecology due to less human disturbance, and is listed as a nature reserve. The sea area from the southern tip of the island to Jihui has beautiful coral reefs and tropical fish, and it is the most beautiful place on the Huadong coastline.

Stone Umbrella is located on the coast 10 kilometers north of Chenggong Town (Provincial Highway 106K, Taiwan No. 11). It extends from the coast to a cape in the sea. It is about one kilometer long. The cape has a little-known name called "Stone Sky Nose”, there is a very peculiar landscape on Shikong Nose called Balance Rock, which consists of a slender rock suspended upwards, supporting a larger rock, forming a special balance structure, which looks like an umbrella The stone umbrella is called the stone umbrella because the upper and lower rocks have different textures. The upper part is a harder coral reef rock, while the lower part is a weaker conglomerate. As a result of differential erosion over time, it becomes thinner at the lower part and thicker at the upper part. The most attractive thing on Shikongbi is the "Stone Umbrella" shaped like an umbrella due to the different corrosion resistance of the rocks. The umbrella surface is hard coral reef, and the umbrella pillar is softer conglomerate. The scenery here is beautiful, and it is a good place for photography. On the west side of the highway stands a huge limestone column, commonly known as the "man's stone" because of its interesting shape, which often makes viewers smile knowingly.