Mi-ja and Young-sook, two girls living on a Korean island, are best friends that come from very different backgrounds. When they are old enough, they begin working with their village's all-female diving collective. Despite their love for each other, Mi-ja and Young-sook's differences are impossible to ignore. Little do the two friends know that after surviving hundreds of dives and developing the closest of bonds, forces outside their control will push their friendship to the breaking point.