Upo Wetland is the largest natural wetland in Korea. The wetland takes up three different areas of Changnyeong-gun with a total size of 2,314,060 square meters. Created approximately 140 million years ago, the wetland was formed when the soft ground collapsed and water filled the area to form swamps and lakes, where dinosaurs played. Dinosaur footprints can be found at Sejin-ri near Upo Wetland.