The northwest coast of the province of Papua in Indonesia is thought to host the largest remaining leatherback nesting population in the Pacific Ocean. We conducted a census of nesting activity at Jamursba-Medi from 2001 through 2004 and of Wermon from 2002 to 2004, and tracked internesting movements of female leatherbacks by using satellite telemetry during the nesting season in 2003. We recorded 1865–3601 nests each season at Jamursba-Medi and 1788–2881 nests at Wermon. Nesting occurred year-round, with a peak in activity between May and September at Jamursba-Medi, and between October and March at Wermon. Comparing these data with previous records of nesting activity from 1981 to 2001 indicates that, although there are indications of a long-term decline, this population has not been depleted to the extent found at other major rookeries in the Pacific. Satellite telemetry indicates that nesters frequent waters around the Raja Ampat Islands and coastal waters to the west of Jamursba-Medi, and may also nest outside the monitored area. We recommend establishing a marine protected area to ensure protection of this population in these critical nearshore marine habitats and implementation of conservation measures in partnership with local communities at these nesting beaches before this population becomes depleted.