Ongjin County is a county in Incheon Metropolitan City, South Korea. It consists of a group of islands in the Yellow Sea.
Four of the islands, Yeonpyeong Island, Baengnyeong, Daecheong, and Socheong Islands, are very near the Northern Limit Line. They are close to the Ongjin Peninsula of South Hwanghae Province in North Korea, at a considerable distance from the nearest part of the South Korean mainland. These islands are popular destinations for tourism. In historical contexts these three islands and their smaller neighbors are sometimes known as the Sir James Hall Group after Sir James Hall, whose son Basil Hall was an early Western visitor to Korea.