Gadeok Island (Hanja: 加德島) is Busan’s biggest island with a legend of Bogae Mountains that is said to have sunken in the ocean and risen up again. Located at the west of Nakdong/Rakdong River estuary, Gadeok Island's size is 1.5 times bigger than Yeongdo Island which is administered by Busan Yeongdo-gu Office.
The Principal Administrative Precinct for Gadeok Island is CheonGa-dong which contains five Legal Precincts in it: Nulcha-dong (Nulcha island), Dongseon-dong, Seongbuk-dong, Cheongseon-dong and Daehang-dong. Thus, there are four legal precincts in this island which are Seongbuk-dong at Gadeok North, Cheongseon-dong at Gadeok Central, Dongseon-dong at Gadeok East and Daehang-dong at Gadeok South.
Gadeok Island serves as the home for the Second Busan Port a.k.a Busan New Port (부산신항), in order to ease naval logistic difficulties in the main port, located at Jungang-dong 4-ga, Busan Jung-gu. The GeoGa Great Bridge and Gadeok-Nulcha Great Bridge connects this island to Geoje Island (Geoje City), Southern Gyeongsang Province and Mainland Busan Metropole (Sinho-dong, Busan Gangseo-gu) respectively.
Centered by the highest peak of Yeondae Peak (459.4m), countless mountains are spread. Gadeok Island’s sceneries, from the white-sand beaches connecting Nulcha-dong and Dongseon-dong to the northeast along the coastline, the open sea by the Prayer's House, to the broad pebble field of Daehang Saebaji to the southeast and Yongdu Rock that lead to the camellia forest, Oedong Islands, Dongdumal, rare-looking rocks on the cliffs by Gadeok Island’s lighthouse, Oeyangpo Beaches to the southwest, long-stretched Solseom Island of Dumun and Cheonsumal Ko Rock, are as beautiful as those of Haegeumgang in Geoje City, Southern Gyeongsang Province.