Generally, coral reefs are found in tropical oceans or subtropical oceans. The requirements of coral reefs include suitable seawater temperature, sufficient sunshine, clean seawater, no diswcharge from rivers, a constant flow of seawater, and an abundance of plankton.

In southern Taiwan, Ken-ting, The Peng-hu Isles, Green Island, and Orchid Island are surrounded by coral reefs. The coral reefs form a unique ecology and became a major attraction to tourists.

Coral reefs can also be found in the northwest coast of Taoyuan Hsien from Nei-hai Village of Da-yen Shiang and passing through Guan-yin Shiang until Shin-wu Shiang in the south. When the tide ebbs, 100-meter long and 20-meter wide dark brown coral becomes visible. The ocean water eroded the coral reef so much that now sea trenches have been created.

Scientific research indicates that the coral reefs were formed five thousand years ago when the glacial period was over, temperature was warmer, and sea levels were higher. After the climate changed the coral ceased to grow and at present no coral is growing. The coral reef of Taoyuan Hsien can be considered a souvenir of the earth's climatic changes. Visitors often find beautiful coral pieces on the beach and keep them as souvenirs. To watch the coral reefs, visitors can walk along Taiwan Provincial Road 15 or seashore highway, then take the small road to the seashore. Visitors are advised to study the tides before they go. Coral reefs become visible when the tide ebbs.