Hashima, Battleship Island

Forty years before it emptied, this rock had the highest population density on earth.

Hashima, commonly called Gunkanjima, meaning Battleship Island, lies about 15 kilometres from the centre of Nagasaki in the East China Sea, one of 505 uninhabited islands in Nagasaki Prefecture. It covers 6.3 hectares. What you see is clusters of abandoned high-rise concrete pressing against a man-made sea wall, a battered shrine at the top of a steep rock cliff, and not a single tree.

The explanation is coal. Undersea mines established in 1887, reached by long descending tunnels, produced huge quantities of high-grade coal for almost a century, and the island's history reads as a chronology of Japan's energy policy from the Meiji period onward. Population peaked at 5,259 in 1959. In 1974, with the reserves nearly gone, the mine closed and the residents left, abandoning the island to wind and salt spray and leaving behind unneeded belongings and a few stray cats nobody could catch.

The island is a symbol of Japan's rapid industrialisation. It is also a reminder of Japanese war crimes, as a site of forced labour before and during the Second World War, and that half cannot be separated from the other.

That tension shaped its heritage listing. The coal mine was approved as a UNESCO World Heritage Site in July 2015, as part of the Sites of Japan's Meiji Industrial Revolution series, after considerable controversy: Japan and South Korea negotiated a deal under which Korea would not object to the inscription and Japan would cover the history of forced labour on the island.

Tourist access reopened on 22 April 2009 after some collapsed exterior walls were restored. Go, and read both histories.