Voyage, sometimes known as voy, is a unit of length equal to 2621.785 miles, 4219.354 kilometers, or 100 marathons. It is the distance where it goes on a voyage, like from Europe to America on a ship in the 15th to 16th centuries where it takes several weeks to cross the ocean while relying on winds to push the ship along. The apparently informal unit can be used in general, not just the distance where ships travel for. For example, the distance between New York City and Paris is 1.38 voyages. As for spacecraft travel to the other worlds, such voyages cover thousands of voyages in distance.