This study determined the movements of a Giant Grouper, Epinephelus lanceolatus, in which an acoustic tag was surgically implanted and monitored by an array of six VR2W acoustic receiver units from August 2010 to January 2013 in the remote, uninhabited Chesterfield Islands, Coral Sea (800 km West of New Caledonia). Our data revealed a home reef area (residency rate of 44.9%) with an increased activity revealed by movements at dawn and dusk toward and between two adjacent reef passages, probably for foraging. The fish was absent from its resident reef between October and December 2010 and 2012, corresponding to the time known for spawning aggregations of this species in New Caledonia. A skipped spawning seems to have occurred in 2011. We hope these data will be complemented in the future by locating the spawning site or sites and thus provide adequate conservation measures. The Coral Sea links two World Heritage Sites, the Australian Great Barrier Reefs and the New Caledonian coral reefs. It would be fitting to create a Marine Protected Area for the Chesterfield Islands between these two major conservation areas of the sea.