There are eight mountains over 400 m (1,300 ft) high.
The tallest mountain is Mount Hongtou or Hongtoushan (紅頭山) at 552 m (1,811 ft).
The rock on the island is volcanic tholeiite andesite and explosive fragments.
The volcano last erupted in the Miocene period.
It is part of the Luzon Volcanic Arc.
Magma was formed from underthrusting oceanic crust under compression about 20 km (12 mi) deep.
The andesite rock contains some visible crystals of pyroxene or amphibole.
The geochemistry of the rock shows that it is enriched in sodium, magnesium, and nickel but depleted in iron, aluminum, potassium, titanium, and strontium.

As the island is within the tropics, the island experiences a warm and rainy tropical climate throughout the year with humidity often reaching more than 90%.
Rainfall, abundant throughout the year, cools the temperature significantly.
The climate is classified as a monsoon-influenced Koppen's tropical rainforest climate (Af) with frequent cyclones therefore not equatorial, with annual temperatures averaging around 23 °C (73 °F) on the mountains and 26 °C (79 °F) on the coasts, one of the highest in Taiwan.

Lesser Orchid Island is an uninhabited volcanic islet nearby.
It is the southernmost point of Taitung County.
It is home to a critically endangered endemic orchid, Phalaenopsis equestris f. aurea.

Forest Belle Rock is located south of Lesser Orchid Island.
There are eight mountains over 400 m (1,300 ft) high. The tallest mountain is Mount Hongtou or Hongtoushan (紅頭山) at 552 m (1,811 ft). The rock on the island is volcanic tholeiite andesite and explosive fragments. The volcano last erupted in the Miocene period. It is part of the Luzon Volcanic Arc. Magma was formed from underthrusting oceanic crust under compression about 20 km (12 mi) deep. The andesite rock contains some visible crystals of pyroxene or amphibole. The geochemistry of the rock shows that it is enriched in sodium, magnesium, and nickel but depleted in iron, aluminum, potassium, titanium, and strontium.
As the island is within the tropics, the island experiences a warm and rainy tropical climate throughout the year with humidity often reaching more than 90%. Rainfall, abundant throughout the year, cools the temperature significantly. The climate is classified as a monsoon-influenced Koppen's tropical rainforest climate (Af) with frequent cyclones therefore not equatorial, with annual temperatures averaging around 23 °C (73 °F) on the mountains and 26 °C (79 °F) on the coasts, one of the highest in Taiwan.
Lesser Orchid Island is an uninhabited volcanic islet nearby. It is the southernmost point of Taitung County. It is home to a critically endangered endemic orchid, Phalaenopsis equestris f. aurea.
Forest Belle Rock is located south of Lesser Orchid Island.
Orchid Island