Oshima Island
Rock walls and a large lava tube
One of the largest lava tubes in the Goto Islands can be found on Oshima Island, the southernmost of the three islands that lie to the east of Fukue Island. Located on the unpopulated southern side of the island, the lava tube extends some 130 meters into the earth. The interior walls consist of brightly shining pyrite crystals, while countless volcanic stalactites have formed on the ceiling. Animals discovered within the lava tube are now being studied by university researchers, who believe some may turn out to be unique to Oshima. Another geographical feature of Oshima is Mt. Hosogatake, a rounded rise on the western side of the island, which is officially the lowest mountain in Nagasaki Prefecture, at 25 meters.
Volcanic rock is used throughout the Goto Islands to build walls around houses, and Oshima is no different. Today the island is home to a population of 50, hosting a post office and a Buddhist temple with a statue-lined garden and large graveyard. Accommodations are available on the island.