On 27 July 1991 I observed a Markham’s Storm-Petrel (Oceanodroma markhami) at 29°59'N, 123°43'W, 293 nautical miles west-southwest of San Nicolas Island, California, and 416 nautical miles due west of Punta Baja, Baja California. I made the sighting at 1245 PST, while censusing birds and marine mammals from a research vessel, as part of a California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruise. The wind was light and high clouds were overhead, resulting in excellent observation conditions. From the bridge of the northbound vessel, about 15 meters above the water surface, I watched the storm-petrel fly toward the bow of the ship from the northeast, zigzag back and forth across the path of the ship 3–5 meters in front of the bow, then fly down the west side of the ship. I had excellent views as the bird banked two or three times in front of me. I then went up to the flying bridge where I resumed watching it for 6–8 minutes as it glided back and forth over the wake, at times tending to follow the ship, until I lost sight of it far to the south. I wrote a complete description of the bird an hour after the observation.