Its area was registered as a world biosphere sanctuary in 2004 for its unique mountainous beauty, valley beauty and rich biodiversity.

The biosphere sanctuary covers over 52, 000 hectares of areas, including the seashore and flat areas of Unryul County and Mt Kuwol with Sahwang Peak (954 m), the highest one in South Hwanghae Province, in its center. And the mountain has boundaries with Unryul, Anak, Samchon and Unchon counties.

The biosphere sanctuary also includes wetland, tideland, rivers and farmland on the coast of West Sea of Korea and hot springs.

There are various kinds of animals and plants in the sanctuary.

The sanctuary is an area of weighty significance in the protection of biodiversity not only in the country but also in the world.