"Gunkanjima" (or "Battleship Island" because of its shape) is an abandoned island built by Mitsubishi corporation. Its sole purpose was to house 5000 residents there to work in its coal mine for 100 years.
In 1974, with the coal reserves nearing depletion, the mine was closed and all of the residents departed soon after, leaving the island effectively abandoned.
The 6.3-hectare (16-acre) island was known for its undersea coal mines, established in 1887, which operated during the industrialisation of Japan. The island reached a peak population of 5,259 in 1959. In 1974, with the coal reserves nearing depletion, the mine was closed and all of the residents departed soon after, leaving the island effectively abandoned for the following three decades.
Interest in the island re-emerged in the 2000s on account of its undisturbed historic ruins, and it gradually became a tourist attraction. Certain collapsed exterior walls have since been restored, and travel to Hashima was reopened to tourists on April 22, 2009. Increasing interest in the island resulted in an initiative for its protection as a site of industrial heritage.
The coal mine of the island was formally approved as a UNESCO World Heritage Site in July 2015, as part of Japan's Sites of Japan's Meiji Industrial Revolution: Iron and Steel, Shipbuilding and Coal Mining.