Dolphin movements were studied with hydrophone arrays and visual observations using the R/P FLIP moored North of San Clemente Island in Fall 2008. A total of 14 hydrophones distributed as two L-shaped arrays at 36 m depth and one vertical line array at 139 m depth were deployed from FLIP. The data were sampled at 192 kHz continuously for 4 weeks. Sound localizations were realized by estimating vertical and horizontal angles from automatically detected dolphin echolocation clicks and whistles to compute ranges, depths, and bearings. While angles to broadband clicks were estimated by cross-correlation, angles to narrow-band whistles were obtained by coherently frequency-averaging conventional frequency domain beamformer outputs. Sound refraction errors were corrected using Snell’s law. The localization methods were groundtruthed by successfully tracking ships and by comparing acoustic and visual positions for dolphin groups. First results reveal continuous trajectories of common dolphin schools for as long as 15 min and suggest that common dolphin actively approaches the FLIP from at least 1 km distance. Common dolphins also appear to be capable of echolocating man-made seafloor instruments at 350 m depth by diving from the surface to approximately 139 m depth while discontinuing whistling.