The basin has a cover area of 1.5-2.0 square kilometers, about 1.5 km from east to west, and about 2.0 km from south to north. Nari basin is a crater basin formed by the collapse of the northern part of Seonginbong(984m)'s caldera, within the eruption of Albong(611m) and the lava from Albong separated into two crater basins. The northeastern part is called the Nari village and the southwestern part is called Albong village where no people live in. The Basin is surrounded by somma, and the Seonginbong is the highest peak of the somma and also the highest peak of Ulleungdo.