The oceanic movements of a captive-raised adult loggerhead turtle ( Caretta caretta) were monitored with satellite telemetry for 368 d from 10 August 1996 to 12 August 1997. During this time the turtle migrated across the Pacific Ocean, covering more than 11,500 km between Santa Rosaliita, Baja California, Mexico (28°40'N, 114°14'W), and Sendai Bay, Japan (37°54'N, 140°56'E). The average speed during the migration was 1.3 km h−1 and the maximum recorded speed was 1.84 km h−1. Our findings are consistent with the hypothesis that loggerheads feeding in the eastern Pacific eventually return to nest on western Pacific beaches, a relationship previously inferred from molecular genetic analysis and flipper tag returns. We conclude that loggerhead turtles are capable of transpacific migrations and propose that the band of water between 25° and 30°N, the Subtropical Frontal Zone, may be an important transpacific migratory corridor.