What is the purpose of a nautical mile?

The purpose of a nautical mile is to measure distances at sea, based on the Earth's geometry. A nautical mile is specifically defined as the distance corresponding to one minute of latitude along any meridian. This makes it particularly useful for maritime and aerial navigation, where distances over the Earth's surface are not linear due to the spherical shape of the Earth.

Using the nautical mile is advantageous because it is directly related to the coordinates used in navigation (latitude and longitude). This relationship allows navigators to easily translate their positions and distances directly based on the Earth's curvature, making it easier to plot a course or determine distance traveled over water. Thus, the nautical mile is essential for ensuring accurate navigation in maritime contexts.