Set on the Island of Jeju, The Island of Sea Women follows Mi-ja and Young-sook, two girls from very different backgrounds, as they begin working in the sea with their village's all-female diving collective. Over many decades -- through the Japanese colonialism of the 1930s and 1940s, World War II, the Korean War, and the era of cellphones and wet suits for the women divers -- Mi-ja and Young-sook develop the closest of bonds. Nevertheless, their differences are impossible to ignore: Mi-ja is the daughter of a Japanese collaborator, forever marking her, and Young-sook was born into a long line of haenyeo and will inherit her mother's position leading the divers. After hundreds of dives and years of friendship, forces outside their control will push their relationship to the breaking point.