The Nakdonggang Estuary, located in Saha-gu, Busan, is an estuarine wetland, designated Natural Monument No. 179 and Cultural Properties Preservation Area. In the estuary are found a wide mud flat and small and large offshore bars formed by sand and gravels built up above the water surface. Since it is where fresh water meets sea water, the surrounding area becomes rich in biodiversity. Therefore, the estuary serves as a home for migratory birds to breed, winter and transit. There are offshore bars of various sizes called Daemadeung, Maenggeummeorideung, Jangjado, Shinjado, Baekhahpdeung, Doyodeung and Jinwoodo. Their sizes change every day as the silt brought down by the river flows, piles up and collapses by the waves of the South Sea. The Nakdonggang Delta, a.k.a. the Nile Delta of Korea, is regarded as the best habitat for migratory birds in Asia, and in ancient times, the Gayan culture flourished in this fertile area. Most rivers in Korea flow into the West Sea. Such a notable feature and a great tidal range hinder fluvial delta formation. For this reason, the delta of the Nakdonggang Estuary bears a high geological and geomorphological value; it is one of a handful of deltas in Korea with a typical appearance in a considerable size. The area has been fully utilized for education through the establishment of eco-tourism infrastructures: natural and restored wetlands, visitor’s center, bird observatory, and vista point. The estuary has been under protection, designated Natural Environment Preservation Area (52.74㎢), Cultural Heritage Designation Area (88.49㎢), Wetland Preservation Area, and Special Management Area of Busan Coast. At the southernmost point of Eulsukdo Island is built a bird observatory where visitors can take pictures of landscapes and migratory birds. Amisan Mountain Observatory, near the end of a geotrail course, offers not only a panoramic view of offshore bars, migratory birds and sea of Busan but also literatures on the geomorphology and geology of the estuary.