At the peak of her career, at the age of 32, Rell was diagnosed with breast cancer. With no family history of the disease, Rell discovered that Native Hawaiian and Pacific Islander women have the highest incidence of breast cancer of all women in the United States. When she realized that detection and prevention programs were seriously underfunded, Rell became a community educator and activist for breast cancer awareness and for the protection of the environment from the toxins she believed had caused her disease. Rell was also a board member of the Surfrider Foundation, an organization devoted to preserving the ocean environment, and served as Hawaii’s surfing ambassador for more than 30 years.

HEART OF THE SEA traces Rell's remarkable personal and public life, interweaving her last interview in 1997 — two months before her death — with breathtaking surfing footage, archival news footage, home videos and interviews with her daughter, friends, fellow surfers, doctors and others in the community whose lives were changed by the way Rell chose to live hers. Although the cancer metastasized and was declared terminal during her 15-year battle with the disease, Rell never let her cancer keep her from her love of surfing. HEART OF THE SEA is poignant testimony to one woman’s radiant spirit that lives on in Makaha, throughout the Islands, and in all who were touched by the life of Rell Sunn.