Komundo or Port Hamilton, officially Geomun-do (Korean: 거문도; Hanja: 巨文島/巨門島; RR: Geomun-do), is a small group of islands in the Jeju Strait off the southern coast of the Korean Peninsula, located approximately at 34°1′35″N 127°18′45″E / 34.02639°N 127.31250°E. The islands are 12 km2 (4.6 sq mi). There are three principal islands, the two larger ones, Sodo to the west (Seo-do, 서도, 西島) and Sunhodo to the east (Dong-do, 동도, 東島) forming a harbor with the smaller island in the center. On this central island, Observatory Island (or Go-do, 고도, 古島), there was a British naval base from 1885 to 1887.
Today, the islands form a part of Samsan-myeon, Yeosu City, South Jeolla Province of South Korea, with the Samsan township offices located on Observation Island. The islands are also part of the Dadohaehaesang National Park.