It’s as easy as A, B, Sea: P for Portolan

Portolan refers to navigational charts dating back to the Renaissance. They were focused on coastal outlines and included seaports, river openings, shoals and hazards. The distance from one point to another was always included. Latitude and longitude were not features on the maps, neither was interior land. Portolan comes from the Italian adjective “portolana” meaning “related to ports or harbors”.