Gyeonggi Province

Gyeonggi Province wraps the landward approaches to Seoul on three sides and meets the Yellow Sea — called the West Sea in Korea — at Incheon on the fourth. The Yellow Sea is a shallow, semi-enclosed basin between the Korean Peninsula and eastern China, averaging around 44 m in depth across most of its extent. That combination — large tidal prism, enclosed geometry, shallow basin — is the recipe for extreme tidal amplification, and Incheon is one of the results: spring tidal range here reaches 8 to 9 m, placing Incheon firmly among the world's largest semidiurnal tide ranges. For comparison, Mont Saint-Michel in Brittany, a location famous precisely for its dramatic tides, has spring ranges of 6 to 8 m. The Bay of Fundy in Canada, the global record-holder, runs 14 to 16 m; Incheon is in the same category of extreme macrotidal coasts, though not at Fundy's absolute maximum. The practical consequences of a 9 m range are significant. At low water, tidal flats extend kilometres from the former shoreline — the Gyeonggi tidal flats are ecologically among the most productive intertidal systems in the world and are listed as a UNESCO World Heritage Site. The Gyeonggi coast has been subject to extensive reclamation: the most dramatic example is Songdo International Business District, an entire city of 600 hectares built on land reclaimed from the Yellow Sea offshore of Incheon, completed incrementally since the late 1990s. Wolmido Island, now a peninsula connected to Incheon's inner harbour by a causeway, holds an amusement park and a row of seafood restaurants looking out over a harbour where the tidal range can leave boats resting on mudflats at low water. Incheon International Airport sits on Yeongjong Island, also connected to the mainland by causeway across tidal flats. The Korea Hydrographic and Oceanographic Agency (KHOA) maintains the authoritative tide gauge network for Korean waters, including the principal Incheon station, which is one of the longest continuous sea-level records in Northeast Asia. Open-Meteo Marine drives the gridded predictions on TideTurtle pages for this region.