Like Green Island, Orchid Island (Lanyu) is a volcanic island that was formed of magma erupting from the ocean floor. Because the peaks of the mountains at the northwestern corner of the island resemble red human heads in the crimson rays of the setting sun, it was formerly known as "Redhead Island." The present name refers to the wild orchids that once grew there in abundance. The humid, rainy climate has cloaked the mountainous interior of the island with a thick rain-forest cover, and has provided it with a countless variety of plant and animal life. Coral reefs are distributed around the island and the warm Japan Current also flows by, attracting vast schools of fish that make this a paradise for deep-sea fishing and skin diving. (Reference: Tourism Bureau, R.O.C.)
Source: The Digital Lan Yu, (http://188.8.131.52/lanyu/home.asp).