巨文岛（韩文：거문도，韩文汉字：巨文岛，英语：Port Hamilton及Geomun-do）是一座位于大韩民国全罗南道丽水市的大陆岛，总面积60.5平方公里，岛屿并分为东岛、西岛与古岛，属于丽水市三山面。岛上有一座1905年竣工的现代灯塔，是整个韩国最早完成并保存至今的现代西式灯塔。目前由中央与地方共管，地方政府是全南丽水市厅，中央则是多岛海海上国立公园管理处之管辖范围。该岛曾于1885年4月15日爆发英国皇家海军与沙俄海军冲突的巨文岛事件。自此，西方学术文档对于巨文岛的称呼为「汉米尔顿港」（Port Hamilton），近期则逐渐改称为巨文岛（거문도） Geomun-do。

Port Hamilton or Komundo, officially Geomun-do in Korean (Hangul: 거문도 [Geomun-do], Hanja: 巨文島 or 巨門島) 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 / 34.02639; 127.31250. The islands are 12 square kilometres. 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.