Hashima island is one of the 505 uninhabited islands in Nagasaki Prefecture off of the South West coast of Japan, standing at 61,000 square metres in size. But the island was not always uninhabited, as it was once home to a major coal mining operation managed by Mitsubishi, at its peak, housing 5,259 people which resulted in a staggering 83,500 people per square kilometre, making it one of the most densely populated places in world history.