The dormant volcano Hallasan formed many of the natural attractions found on Jeju. As South Korea’s tallest mountain, Hallasan offers an abundance of hiking opportunities and is an UNESCO Biosphere Reserve showcasing a crater lake and an abundance of plants and wildlife. The Manjang Cave, formed by cooling lava, is the world’s longest lava tube and is partially open for tours. Head from the mountain to the magnificent beaches and watch famed haenyo (powerful sea-women) dive for octopus, abalone, clams and more without the aid of a breathing apparatus. Don’t miss the opportunity to sample fresh seafood dishes at a local restaurant.