"Portola's Expedition and the Discovery of San Francisco Bay" is a book that tells the story of the fascinating travel selection of the first official extensive survey of lands along the west coast of North America led by the Spanish officer and colonizer Pedro Fil Miguel Fresnadey Portola. Authors Eldridge and Mohler interweave through Portola's thinking and actions, as well as performed mathematical modeling of the location on the map of the places he visited. The book offers not only an overview of historical facts, but also answers questions about the connection between Portola's voyage and the discovery of San Francisco Bay, which makes it interesting not only for historians, but also for the general public.