In order to have a thorough grasp of sea route to meet with the demand of economic development and national security, the Nguyen kings took practical measures in restricted technical conditions, such as the work of drawing maps or.setting up landmarks in the waters and estuaries, state boats were dispatched to remote areas and islands to "survey sea route" or set up landmarks. They all served the target of affirming the sovereignty over the waters of the country. In addition, there were regular sea transport activities of both merchant ships and state ships in the waters every year to convey goods and rice from the North and the South to the capital city, combining the tasks of transport and patrol of the protected waters. On approaching historical books of the Nguyen Dynasty, the author initially outlines those important activities.