Measured in metres (or feet) which is longer, the land mile or the nautical mile? How much is the difference and why is this so?

Nautical miles are used to measure the distance traveled through the water. A nautical mile is slightly longer than a mile on land, equaling 1.1508 land-measured (or statute) miles. The nautical mile is based on the Earth's longitude and latitude coordinates, with one nautical mile equaling one minute of latitude.

But why use a different measurement system for marine navigation? Using latitude and longitude coordinates is more practical for long-distance travel, where the curvature of the Earth becomes a factor in accurate measurement. Nautical charts use latitude and longitude, so it's far easier for mariners to measure distance with nautical miles. Air and space travel also use latitude and longitude for navigation and nautical miles to measure distance.

The word "mile" might leave you wondering if there's a "nautical kilometer," too. There's not. The international nautical mile is used throughout the world. The measurement was officially set at exactly 1.852 kilometers in 1929 by what is now known as the International Hydrographic Organization. The U.S. and the United Kingdom both used slightly different measurements after that time, but the U.S. adopted the international nautical mile in 1954 and the U.K. in 1970.