4. Gunkanjima, Japan
This is known as the forbidden island. It’s around 15km away from Nagasaki. In 1890 Mitsubishi bought the island and began mining coal. They built apartments for their workers and the population on the island boomed. However, in the 1960s when oil became the preferred fuel, a lot of coal mines closed down. In 1974 the mine was officially closed and everyone moved from the island.
Travel to Gunkanjima is currently prohibited but it was the setting for the 2003 film Battle Royal II.