Despite dating back over 400 years the relevance of traditional fisheries management in Aceh, Indonesia, still remains high. Aceh was, however, greatly affected by the December 2004 Indian Ocean tsunami that claimed an estimated 167,000 lives, including 14,000 fishermen and 59 of the 193 traditional marine leaders (Panglima Laot). This tragic loss of life was accompanied by a substantial loss of local knowledge, such as the locations of hazardous fishing grounds. In this study we describe an innovative project that sought to rebuild a post-tsunami fisheries sector by re-engaging and empowering the Panglima Laot. During April–June 2008 GPS (global positioning system) sounding devices were installed on 53 local fishing boats and hazardous fishing areas mapped based on local knowledge, and shared amongst fishermen. During July–December 2008 nearly five million GPS data points were collected, from which detailed bathymetric maps were produced and shared between fishermen and Aceh government officials. Significant project outputs included a map of fishing areas over 20,000 km2, which included three new seamounts, one of which expanded Aceh's provincial boundary by > 1.3 million ha, and a Panglima Laot decree that reduced fishing in hazardous areas of high coral density by 23.3%. Our findings have wide applicability. Locally, the introduction of GPS technology and sharing of traditional knowledge resulted in fishermen developing and implementing their own management strategies and demonstrating their ability to stay out of restricted areas. Provincially, this project provided a framework through which government agencies and academic institutions could effectively engage with local customary leaders and their fishing communities.