Seongsan Ilchulbong is a 182m volcanic cone at Jeju's eastern tip, formed when magma erupted in shallow sea about 5,000 years ago. Its summit holds a vast bowl-shaped crater some 600m across, ringed by 99 jagged rock peaks like a crown. It was inscribed as a UNESCO World Heritage site in 2007.
True to its name — 'Sunrise Peak' — the sun rising over the crater ridge is a spectacle. The stair path to the top takes just 20–30 minutes, doable for most ages, with sweeping views of Seongsan harbor and Udo island the whole way up.
At Gwangchigi Beach below, low tide reveals green mossy rocks you can frame with the peak — a photographer favorite. Ferries to nearby Udo island make it easy to combine into one trip.