Hashima Island, also known as Gunkanjima, is an island located about 15 kilometers (9 miles) from the city of Nagasaki, southern Japan. There are undersea coal mines, established in 1887, almost 80 years after coal was originally discovered on the island. It had its peak population in 1959 with 5,259 residents living on the island. In 1974, as the coal reserves slowly depleted, the mines were closed and people left.

It remained abandoned until early 2000s when interest in the island's undisturbed historic ruins emerged. The government restored some of the buildings and tourists were allowed to visit Hashima since 2009. In 2015, the island was approved as a UNESCO World Heritage Site.