Jeju Island is formed by lava flow streams with the Mt. Halla in the center. The Mt. Halla`s crater or other parasitic volcano produced lava flows creating lava plateau in this area. There are one thousand volcano caves in the world, and 50% of them are located in the west coast of United States. There are 186 volcano caves in Italy, 100 in Mt. Fuji, Japan, and 70 in Jeju Island. Jeju Island`s east-west axis four sides are world-renown volcano zones with basalt strata that feature low viscosity and fluidity.