Seongsan Ilchulbong Tuff Cone was created by hydrovolcanic eruptions 100,000 years ago.
The peak was once an island, but it is now connected to Jeju Island, due to the sand and gravel washed ashore from Shinyang Beach. Farmers used to grow crops on it.
About 200 varieties of plants and animals live on it. Udo Island is to the north and Seopjikoji is to the south.
The peak is a prime spot from which to view the sunrise. It was designated as a natural monument on July 19, 2000; a UNESCO World Natural Heritage site on July 2, 2007; a Global Geopark on October 1, 2010; and one of the New7Wonders of Nature on November 12th, 2011.