Hashima Island, Japan
Hashima Island was once known for its undersea coal mines, which began operations in 1881. The island hit peak population in 1959 with over 5,000 residents (mine workers and their families), but once the mines started to run dry in 1974 most people left.
The once-thriving island is now completely abandoned, with the exception of the sightseeing tours that drop off boatloads of tourists each day who come to see the abandoned homes, stores, and streets. The island was also featured as a villain's lair in the Bond movie, "Skyfall."