Seoul (Metropolitan) Subway Line 1 of the Seoul Metropolitan Subway, is a commuter rail service which links central Seoul, South Korea to Soyosan Station in the northeast, Incheon in the southwest, and Sinchang via Suwon and Cheonan in the south. The central underground portion of this rail line is the oldest subway section in the Seoul Metropolitan Subway system; the entire rail line covers a large part of the Seoul Capital Area.