The Sinan Dadohae Biosphere Reserve is located in the southwest of the Republic of Korea and consists of 1,000 islands including Heuksando, Hongdo, Bigeumdo, Dochodo and Jeungdo.

A large tidal flat, an important habitat for marine animals and rare migratory birds, also supports fishing and salt production for local people.

The temperate evergreen broadleaf forest includes dominant species such as Castanopsis cuspidata, silver magnolia, and camellia trees.

The dune vegetation zone includes Ischaemum anthephoroides, Zoysia macrostachya, Vitex rotundifolia, Calystegia soldanella, Messerschmidia sibirica, and a colony of Carex kobomugi on Jeungdo Island.

The biosphere reserves has two sites that are part of the Ramsar Wetland Convention, Jangdo Island High Moor and Jeungdo Tidal Flat.