A league is a traditional maritime distance unit equal to 3 nautical miles, or approximately 5.56 kilometers.
Why It’s Rarely Used Today
Modern professional navigation — charts, GPS, radar, passage planning — is built entirely around the nautical mile, not the league. A league survives mainly in historical maritime texts, literature (Jules Verne’s Twenty Thousand Leagues Under the Sea being the most famous reference), and occasional traditional or informal usage, rather than in actual working navigation.
The Relationship to the Nautical Mile
Since a league is defined as 3 nautical miles, converting is straightforward: multiply nautical miles by 1/3 to get leagues, or leagues by 3 to get nautical miles. In practice, this conversion is rarely needed in professional maritime work today.
Exam Relevance
The league is occasionally referenced in general maritime knowledge questions, primarily to confirm a candidate understands it as a historical unit rather than one used in modern practical navigation — the nautical mile is what’s actually tested for real calculation work.