Dokdo (Natural Monument No. 336) is a volcanic island created from hardened lava formed at about 2,000m. It consists of Dongdo Island, Seodo Island and more. The doc is located at Dongdo Island and is full of visitors every day. According to Samguk Sagi, Dokdo became our land after the subjection of Usan-guk to King Jijeung in his 13th year (512), which makes Dokdo clearly our land since A.D. 512.