Green Island (Traditional Chinese: 綠島; Pinyin: Lǜ Dǎo; POJ: Le̍k-tó) is a small volcanic island in the Pacific Ocean, about 33 km (20.5 miles) off the eastern coast of Taiwan. In the 19th century it was known as Samasana Island and the Japanese called it Kasho-to (火燒島). The island is 15.092 km² at high tide and 17.329 km² at low tide. Administratively, Green Island is Lutao Hsiang (綠島鄉), a township of Taitung County and one of the county's two offshore areas (the other is Orchid Island, or Lanyu). Green Island is the ROC's fourth-largest island. It is accessible by airplane in eight to 12 minutes from Taitung City. There are also ferries capable of carrying over 250 passengers.

Prisons
The island is primarily noted as the place of past and current prisons and penal colonies. Green Island first served as an isolated spot and place of exile for political prisoners during the martial law period of Taiwanese history during Kuomintang single-party rule (especially during the White Terror). After their release, many of the prisoners jailed between the late 1940s and the late 1980s went on to establish the Democratic Progressive Party, most notably Shih Ming-teh. Author Bo Yang was also a prisoner here.
The place where most of the political prisoners (such as Shih Ming-teh) were held was the Green Island Lodge (Lǜ Dǎo Shānzhuāng), where conditions were reported to be very bad. Oasis Village was the main penal colony. The prison was later closed, but its interior is not open to the public. There is a current movement to restore the prison and preserve it as a museum.
The Green Island Prison (Lǜ Jiānyú) is also located on the island and has housed some prisoners that have been perceived to be amongst Taiwan's most dangerous criminals and gangsters. However, this has changed in recent years.
The island is the natural habitat for deer, goats, chameleons, giant bats, and coconut crabs as well as indigenous and migratory birds.
In 1995, less than half of the registered 2,634 residents of the island actually reside on the island. The population is dwindling due to difficulty to find jobs on the island. There are two preschools, one kindergarten, two elementary schools, and one middle school on the island. To pursue any education at the senior high school level or higher, the islanders must move to the main island of Taiwan. Public service centres include one seniors' home, one library, and one community centre.
The island was originally inhabited by the Ami Taiwanese aborigines, who called it Sanasai. It was called "Fire-Burned Island (火燒島, Huǒshāo Dǎo, or 火燒嶼, Huoshao Yu) before renamed to Green Island in August 1, 1949 by Huang Shih-hung (黃式鴻), the magistrate of Taitung at the time, who thought that the former name was unrefined.
The villages and the settlements (聚落) they administer are:
The following abandoned aboriginal tribal settlements also belong to Gongguan Village:

Zhongliao Village (中寮村)

• Zhongliao
  Nanliao Village (南寮村)
  
  
  
  • Nanliao (南寮)
    Yugang (漁港)
    Gongguan Village (公館村)
    
    
    
    • Gongguan (公館)
      Chakou (柴口)
      Liumagou (流麻溝)
      Dahu (大湖)
      Zuoping (左坪)
      Youzihu (柚子湖)
      Nanzihu (楠子湖)
      Haicanping (海參坪)
      Dabaisha (大白沙)