In 1968, Hallyeohaesang National Marine Park was designated as the fourth national marine park in Korea. Hallyeohaesang is a unique marine ecosystem which extends along the 120km shoreline from Geoje in Gyeongsangnam-do province to Yeosu in Jeollanam-do province.
The total area which comprises of the Sangju-Geumsan Mt. district, NamhaeDaegyo bridge district, Sacheon district, Tongyeong-Hansando Island district, Geoje-Haegeumgang Island district, and Yeosu-Odongdo Island district is 545.63㎢ of which 72.3% is sea area. Hallyeosudo which is known as the most beautiful waterway ever has 69 uninhabited islands and 30 inhabited islands spread out across the sea like jewels.
The sedimentary rocks from the Mesozoic age create a mountainous range stretched out from the northeast to southwest, and the many capes, islets, and peninsulas constitute a typical rias coast.
Hallyeohaesang National Park has a total of 1,142 plant species including major species such as Red pine, Black pine, Common camellia, Serrata oak, Cork oak as well as rare species such as nadopungnan(Sedirea japonica), Daeheongnan(Cymbidium nipponicum) and the Korean winter hazel. The major animal species are Otter, Small-eared cat, and Badger. Overall there are 25 mammal species, 115 bird species, 16 reptile species, 1,566 insect species, and 24 freshwater fish species.