Thank you for posting about your visit to Gunkanjima. Gunkanjima is on my to do list next time I visit Nagasaki. I am glad that the tour is focused more on history aspect. Along with Ginkanjima, Yubari in Hokkaido and kita-kyushu tells history of coal mining in Japan, once was the major industry in Japan. Having Gunkanjima listed as a World Heritage Site by UNESCO is bringing light to the history of coal mining industry of the past in Japan. It is hard to imagine living at such island densely packing in concrete high rise buildings.