There are four large and small swamps around the Yibang-myeon, Daehap-myeon, and Daeji-myeon areas of Changnyeong-gun, which are collectively called ‘Upo Wetland’. They are the largest natural swamps in South Korea, with a total size about 5,550 square km. The bottom of the swamp is shallower than 1m and there are over 1,000 species living in its murky waters. It has a primitive atmosphere with 100 kinds of plants containing 28 kinds of aquatic plants and 72 types of hydrophytes.Upo Wetland is a primitive low bed wetland, which was created about 140 million years ago. When soft ground collapsed, water started to come to a low basin, and this was a lake where dinosaurs lived 100 million years ago. Upo Wetland was formed in with the sediments from the mountains brought in by rivers. From the outer edge, the current Upo Wetland is going through natural alteration and ecological succession from a lake to swamp and from grass-covered plain to a forest. At Upo Wetland there are eight famous sites such as fireflies, constellation gazing, and willow groves, but there are many, many other interesting things to see. Among the eight famous sights, the Upo rain-fog is an especially eye-catching natural phenomenon, becoming visible when there is no wind, when skies are clear, and the temperature difference between day and night is 10 degrees or more. The fireflies come out around 8~9 P.M. in August and September, and they are also worth watching. In winter, migrating birds spend their winter here and you can watch about 33 species of birds such as swans, whopper swans, bean geese, teals and wild ducks. It is better to take a walk in the evening or early in the morning rather than in the daytime, it would be great also to visit in the night under the starlight.