Ongjin County (Korean: 옹진군) is a county in Incheon Metropolitan City, South Korea. It consists of a group of islands in the Yellow Sea.

Incheon, formerly Jemulpo or Chemulp'o (제물포) until the period after 1910, officially the Incheon Metropolitan City, is a city located in northwestern South Korea, bordering Seoul and Gyeonggi to the east. Inhabited since the Neolithic, Incheon was home to just 4,700 people when it became an international port in 1883. Today, about 3 million people live in the city, making it South Korea's third-most-populous city after Seoul and Busan.