Dolphinfish (Coryphaena hippurus) are circumtropical migratory species of significant importance to recreational, sport, and commercial fisheries. In the western North Atlantic, dolphinfish occur from the Georges Bank, off New England, south to Trinidad and Tobago. Throughout this distribution there have been no studies on the vertical movements of dolphinfish. Understanding these is essential in defining dolphinfish preferred habitat, daily diving patterns, feeding strategies, and predator-prey relationships. We deployed pop-up satellite archival transmitters (PSATs) on 11 adult dolphinfish (95 120 cm estimated fork length (FL)) from 2005 2011 in the western North Atlantic to investigate vertical movements and habitat use. For the first time data was recorded indicating the species use of the vertical water column to depths of at least 255 m. Diving behavior was classified into four time periods, dawn, day, dusk, and night. Dolphinfish spent 66% of their time in the surface layer (0 9.9 m). The most extensive vertical movements (> 30 m) occurred during night rather than during the day. Results suggest a diel activity pattern. These data can be used to further define factors limiting dolphinfish vertical movements, improve stock assessments, resource allocation, and stock-based resource management.