Recently in response to my blog about the San Francisco Bay Sea Serpent, one comment maker wrote in to mention this news item:
By now everyone who is connected by radio, tv, internet or newspaper is aware that James Gray of Microsoft has just disappeared from the face of the earth while expertly sailing his 40 ft sailboat on a day cruise under nearly perfect condition, through very well known waters, to the Farallon Islands. Speculation as to his whereabouts is wide-open and even the most serious and likely suggestions underscore just how slight is the ability of our human perceptions to be able to actually see what's going-on around us. The idea that there can't be something previously unknown on the order of a large animal living out in waters all around us because if it were there we'd have seen it and photographed it...well, that greatly overestimates our powers of observation, not to mention our ability to photograph stuff.- dogu4
I am in no way endorsing any connection between this California coastal disappearance and any assumed behavior of Pacific Ocean Sea Serpents, but open-minded attention to data is usually a good idea. Here's more information on the James Gray story from Boing Boing:

Database pioneer James Gray, winner of the 1998 Turing Award and founder of Microsoft's Bay Area Research Center, is missing off the coast of Northern California. On Sunday [January 28, 2007], he set out alone on his 40-foot sailboat to the Farallon Islands where he intended to scatter his late mother's ashes. He hasn't returned. The US Coast Guard is searching for Gray by boat, plane, and helicopter. Gray is known for such groundbreaking projects as the SkyServer and TerraServer. - David Pescovitz
For more on this topic, in general, see: Death by Sea Serpent?