The Log from the Sea of Cortez is a book written by John Steinbeck, published in 1951, which details a six-week marine specimen-collecting boat expedition he made in 1940 at various sites in the Gulf of California (also known as the Sea of Cortez), with his friend, marine biologist Ed Ricketts. It is regarded as one of Steinbeck's most important works of non-fiction chiefly because of the involvement of Ricketts, who shaped Steinbeck's thinking and provided the prototype for many of the pivotal characters in his fiction, and the insights it gives into the philosophies of the two men.The Log from the Sea of Cortez is the narrative portion of an unsuccessful earlier work, Sea of Cortez: A Leisurely Journal of Travel and Research, which was published by Steinbeck and Ricketts shortly after their return from the Gulf of California, and combined the journals of the collecting expedition, reworked by Steinbeck, with Ricketts' species catalogue. After Ricketts' death in 1948, Steinbeck dropped the species catalogue from the earlier work and republished it with a eulogy to his friend added as a foreword.