This is the most comprehensive book on the geology of the San Juan Islands in the past nine decades. Although written primarily for non-geologists, it also contains much new, previously unpublished geologic material of interest to geologists. The book includes geologic descriptions of the geology of all of the islands with more than 400 photos, maps, and laser, sonar, and satellite images, cross-indexed so the geology of any specific island can be easily found. An appendix of seafloor images is also included.