Hyeopjaegul and Ssangyonggul Lava Caves are considered to have been made because of an eruption of Mt Hallasan around 25 million years in the past, and they are thought to happen to be underneath sea degree at the time due to presence of fossilised abalone shells and various seashells. Jeju https://travis65d0j.qodsblog.com/26965056/jeju-paradise-lsland-things-to-know-before-you-buy