Subsurface Lagrangian measurements at about 140 m showed that the path of the California Undercurrent lay next to the continental slope between San Francisco (37.8 ¿N) and St. George Reef (41.8 ¿N) during mid-summer 1993. The mean speed along this 500 km path was 8 cms-1. The flow at this depth was not disturbed by upwelling centers at Point Reyes or Cape Mendocino. Results also demonstrate the ability to acoustically track floats located well above the sound channel axis along the California coast.