A compass rose on a nautical chart shows both magnetic and true north directions, helping navigators to plot courses.
Buoys, lighthouses, and daymarks are all navigational aids used to mark the edges of channels and indicate safe water.
The Global Positioning System (GPS) is the primary tool for determining a vessel's precise position in modern marine navigation.
Nautical charts provide critical information about water depths, hazards, and other navigational aids necessary for safe passage.
Variation is the angular difference between magnetic north and true north, which must be accounted for in navigation.