Battleship Island, Gunkanjima in Japanese, is the nickname of this place located about 15km off the coast of Nagasaki. Its official name is Hashima Island.
The island got its characteristic shape through a man-made built-up when it served as an undersea coal mine. In its heyday more than 5,000 miners called the island home, making it the world’s most densely populated place. After coal was replaced by petroleum and production came to a halt, all inhabitants left the island.
40 years after its shutdown, the island was reopened for tourism. Today, a handful of operators offer guided tours from Nagasaki port. As a visitor you are, however, restricted to a few hundred meters of fenced walkways. Since the island’s structures are prone to collapse anytime, the authorities have banned any direct access to them.
Should you like to take a closer look, Google has extensive coverage of the place through its street view technology. Their footage even lets you peek into the abandoned buildings, showing tube TVs, discarded soda bottles and other remains of Gunkanjima’s former inhabitants.