About Observation Post #10 Half Moon Bay, California, United States Captain Bob and Sherry of the Queen of Hearts, a 50-foot sport fishing vessel, reports during their Gray whale watching trips January through April. "By the beginning of March we could be in full-swing whale watching just off the San Mateo coastline." Latest News >> Can you see the two whales? One is blowing. Photo: Tom Kotzebu Half Moon Bay, California (37.50N, -122.40W)