Gunkanjima (Hashima Island)

Gunkanjima, officially known as Hashima Island, is a striking abandoned island located 15 kilometers off the coast of Nagasaki. The island operated as a coal mine from the 1880s until 1974 and at its peak housed over 5,000 residents in Japan's first concrete apartment buildings, making it the most densely populated place on Earth. After the mine closed, the island was abandoned and left to decay, creating an eerie landscape of crumbling concrete structures. Designated a UNESCO World Heritage Site in 2015 as part of the Sites of Japan's Meiji Industrial Revolution, the island is accessible via boat tours departing from Nagasaki Port. Tours are weather-dependent and visitors walk a designated path around the southern tip of the island, so check conditions before booking.