Namhae-gun is comprised of Namhae Island and Changseon Island.
Namhae is adjacent to Hadong-gun and Sacheon on the north, Tongyeong on the east, Gwangyang and Yeosu of Jeollanam-do Province on the west and the Straits of Korea on the south.
Namhae Island has an area of 357.66km2 and it measures approximately 26 kilometers across, east to west, and 30 kilometers from north to south. It is the 5th largest island in Korea. The terrain is very mountainous and the island has mountains like Mt. Mangun (786m), Mt. Geum (681m), and Mt. Won (627m) and all the streams are shorts and the plains are also very small and narrow.
| Category | Location | Longitude and Latitude |
|---|---|---|
| Far East | Gudol Island, Mijo-myeon | 128°07´ East Longitude |
| Far West | Deungdaegot, Yeomhae-ri, Seo-myeon | 127°48´ East Longitude |
| Far South | Sejon Island, Sangju-ri, Sangju-myeon | 34°29´ North Latitude |
| Far North | The light house at Suwon-neul, Wangji-ri, Seolcheon-myeon | 34°56´ North Latitude |
The 302km-long coastline is very curvy and convoluted, making it an ideal location rich marine resources and coastal fisheries. There are 3 inhabited islands; Jo Island, Ho Island, and No Island and 76 uninhabited islands and also, large sand bars near the river-mouth of Seomjin River in the northwest region.