We document and describe the change in attitudes, hunting behaviour and historic subsistence use of sea turtles by Cocos Malay people of Islamic faith in the Cocos (Keeling) Islands, Indian Ocean over the last 180 years. We used several lines of evidence including historical documents, scientific journals, archived records and interviews with current and former residents. The results are grouped in two time categories: 1) use of turtles prior to mid-1980s and 2) use of turtles after mid-1980s. Prior to the mid-1980s, turtle meat was popular with Muslim residents and was consumed when available and was particularly appreciated during times of ceremony. After the mid-1980s, external influences and improved communication modified Islamic teachings and sea turtles were reclassified from halal (permitted as food) to haram (prohibited as food). After the mid-1980s, harvest and the use of turtles decreased to negligible numbers. Although a combination of various events and circumstances may have contributed to this change in harvest practices, changes to Islamic teachings were likely to be the main factor. These changes in use appeared to have had a dramatic positive effect on the resident green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtle populations, from what appeared to be harvest-related depressed numbers prior to the 1980s, recovering to abundant numbers after 1999. From a management perspective, this is a positive conservation outcome for sea turtles, at both local and regional (Indian Ocean) scales