The coast of Vietnam is located at the heart of the maritime trade routes that connected China and Island Southeast Asia. During the 16th–19th centuries, as the Nguyễn Lords settled and developed central Vietnam also known as Cochinchina, maritime trade flourished in concert with the arrival of the Europeans in the region. The voyages from Europe to the East Indies were long, navigators had to master new trajectories, the trips needed to be conducted as fast as possible to face competition and above all, to comply with the local calendars of the prevailing monsoon winds in order to enter the South China Sea and travel to China. Their cargoes were precious, life on board arduous, and the waters they sailed were unknown. Hence, charting the seas was a fundamental endeavour for competing trading nations between the 16th and 19th centuries to help minimize risk of loss. This paper discusses the maritime routes along the coasts of Champa and Cochinchina throughout the 16th to the 19th centuries, and above all, the charts and instructions that European navigators had in order to navigate safely in the perilous waters of the South China Sea. Unfortunately for the historian or maritime archaeologist, there is very little on the making of Southeastasia’s cartography. There are only few sources in non-European languages on navigation in the South China Sea, and much less on the charting of the Vietnamese waters. Local routes and maritime movements of Cham and Cochinchinese fishers, naval officers and traders are, so far, less clearly delineated than those of European navigators and not readily decipherable. However, European seafarers based themselves on the local knowledge of Malay, Chinese and Vietnamese seafarers, who guided them through safe harbours, sometimes sailed their ships, and provided navigation advice. The following chronology will henceforth also put in perspective the fact that the charting of the Vietnamese coastline was not only the effort of one European nation but the result of a global conjunction that had roots in local experience.