Once a major coal mining operation managed by Mitsubishi, Hashima Island, located in Japan, housed 5259 people at first, then grew to a staggering 83, 500 people per square kilometre, making it one of the most densely populated places in the world. This relentless coal mining went on through 2 world wars. In the 1960's the popularity of petroleum grew immensely, and coal mining fading, thus the closure of this coal mining operation in 1974, and it has been abandoned since.