Dudo Island geosite belongs to Seo-gu, Busan and has been designated Natural Park since 1972. This uninhabited island is 500 m away from the southwest of Amnam park in Amnam Peninsula and is a home for camellia, cleyera, black pine, coral reef, and seagull, a mascot bird of Busan. Visitors will be blown away by the view of Hallyeohaesang National Marine Park and an outstanding harmony between volcanic rocks and the lower part of the Dadaepo Formation developed along the sea cliffs during the late Cretaceous. The site is expected to shed light on the sequence of strata in the Dadaepo Formation, a controversial issue in academia, thanks to its well-exposed outcrops of the plane of unconformity between Yucheon Group volcanic rocks and the lower part of the formation. In the lower part of the formation are observed geological heritage such as fossils of dinosaur egg nests and petrified woods and geological structures like normal faults, strike-slip faults, a flower structure, and dikes. Close to the land, the Dudo Island geosite makes a great place for many anglers and also has an unmanned light house which guides ships and boats.