Nautical mile

The nautical mile, often referred to as a sea mile, is a unit of length equal to exactly 1,852 metres. Historically defined as one minute of latitude arc along a meridian of Earth, the unit was formally standardized to its modern metric figure by the International Hydrographic Organization in 1929. It remains the global standard unit for maritime and aerial navigation, directly forming the basis for the speed unit known as the knot.