The first printed isobath map

Detailed sea depth data and hydrological observations for the first printed isobath map were collected by Marsigli in the Gulf of Lion three hundred years ago. This map, an annex to his large and comprehensive volume on the seas, has been considered one of the forerunners of thematic maps. Although the cartographic and oceanographic literature often refers to Marsigli’s map, several authors have misinterpreted the data and information contained in the map. This paper re-examines the map legend and the drawing of the map, compares the first isobath map with a modern map of the area, and finally evaluates Marsigli’s contribution to earth sciences