Convert from stadium to league [nautical]

Unit Definition (stadium)
The stadium is a historic unit of distance originating in ancient Greece. Greek athletic fields were all of roughly the same size, and the stadion, equal to 600 podes (feet), was the traditional length of the field. Archaeological measurements show that the stadion was a little more than 200 yards or a little less than 200 meters. The stadion at Olympia, where the original Olympic Games were held, measures 630.8 feet or 192.3 meters; at Athens the stadion was 606.9 feet or 185.0 meters. Stadium is the Latin spelling; in the Roman world the stadium was equal to 625 Roman feet (pes) or 1/8 Roman mile. This is equivalent to 606.95 feet, 202.32 yards, or 185.00 meters. The plural is stadia.

Unit Definition (league [nautical])
The nautical league is approximately equal to three nautical miles, 1/20 degree, or 5556 meters (metres). Note that it is not equivalent to the portugese, french and spanish measurements of the league. The nautical league is also different from the league defined on land.