There is more than one type of Nautical Mile
There are a few different types of Nautical Mile. On this site we have conversions for US Nautical miles, UK Nautical miles and International Nautical miles. Please either select the appropriate unit on the selection above of click the required unit in the links below:
What is a nautical mile?
A nautical mile is the unit of distance at sea and in the air, and is exactly 1,852 meters. It began as one minute of latitude along any meridian, which varies slightly because the Earth is not a perfect sphere, so a fixed length was agreed internationally.
Latitude is the reason for the length: a degree has 60 minutes, so a nautical mile is a sixtieth of a degree and 21,600 of them go round the Earth. That makes the latitude scale on a chart a distance scale too. Territorial waters extend up to 12 nautical miles from a coast.
What is a League?
A league was originally roughly the distance a person could walk in an hour, about 3 miles (4.8 kilometers). The exact length varied with the country and the period.
A league is an old unit of length, usually around 3 miles or 5 kilometers, though the exact figure varied by country and period. Jules Verne's Twenty Thousand Leagues Under the Sea is about distance travelled, not depth – 20,000 of his 4 kilometer leagues is 80,000 kilometers, twice around the Earth.