From afar, the Unesco World Heritage island of Hashima resembles a battleship, hence its nickname Gunkanjima ('battleship island'). Up close, this long-abandoned coal mine looks as though it's straight out of an apocalyptic manga (even appearing as the villain's lair in the 2012 James Bond film Skyfall). Once earth's most densely populated place, it became a ghost island when the mines were closed in 1974, and it's been left to nature since, now accessible only by guided tour.

　　Access is restricted because so many structures have collapsed or been damaged that much of the island is unsafe. Guided tours allow visitors to ramble on walkways among the long-disused skyscrapers. Some of the architecture (such as the iconic 'X' stairways – alas, not visible on the tour) was considered remarkable for its time, as engineers tackled the challenges of designing for such cramped living.

　　While most of the spoken guiding is in Japanese, English info is available. Three-hour cruises from Nagasaki run twice daily from April to October; there are fewer departures November to March. Contact Gunkanjima Concierge for reservations.