Vocabulary of Life by the Sea
"Knots" and "nautical miles" are good old navy terms. Originally, the nautical mile was based on the circumference of the earth at the equator, so if anyone ever asks the distance around the earth, do the math (360 degrees X 60 minutes per degree) and say "about 21,600 nautical miles!" One minute of longitude at the equator is equal to one nautical mile.