At 1415 on 2 November 1991 we found an Arctic Loon (Gavia arctica sensu stricto) at Abbott’s Lagoon, Point Reyes National Seashore, in Marin County, California. We observed the bird for about an hour at ranges down to about 250 m with binoculars and spotting scopes. It was a clear day, and we had the sun at our backs. After completing field notes and sketches, we returned home to consult the literature and notify other birders. We returned the following morning and, with several other birders, soon located the loon and observed it for over 2 hours. Additional notes were taken as the bird swam intermittently to within 100 m and then farther out into the fog. The following description and Figures 2 and 3 are derived from our notes and sketches taken from 1415 to 1515 on 2 November and from 0845 to 1100 on 3 November. The bird was last reliably reported on 17 November. Other observers photographed and videotaped (Figure 1) the bird, and the identification has been accepted by the California Bird Records Committee.