Hashima Island (Battleship Island / Gunkanjima)

Hashima Island, nicknamed Gunkanjima ('Battleship Island') for its silhouette, is a 6.3-hectare islet roughly 19 kilometers from Nagasaki Harbour that was mined for undersea coal from 1887 to 1974 under Mitsubishi ownership. At its peak in 1959 it housed over 5,300 residents at a population density among the highest ever recorded worldwide, packed into Japan's first large-scale reinforced-concrete apartment blocks, built from 1916 onward to withstand typhoons. During the Second World War, Korean and Chinese laborers were conscripted to work the mine under harsh conditions, a history acknowledged as part of the island's 2015 UNESCO World Heritage inscription under the 'Sites of Japan's Meiji Industrial Revolution' listing. The mine closed in 1974 as Japan shifted to petroleum, and the island was abandoned within months, leaving apartment blocks, a school, and a hospital to decay under sea exposure for four decades. Tourist access reopened in 2009 via a restricted walkway along the island's southern edge, covering perhaps a tenth of the total site; the interior apartment blocks remain closed due to structural collapse risk. Guided landing tours depart from Nagasaki's Ohato Terminal and combine a boat circuit of the island with a short walk along the reinforced concrete seawall, past collapsing stairwells and the skeletal remains of the mine's shaft towers.