It's about one-and-two-fifths times as tall as Olympus Mons.
In other words, the height of Olympus Mons is 0.71 times 509 leas.(a.k.a. Mount Olympus) (Mars)
It's about two-fifths as long as The Panama Canal.
In other words, 509 leas is 0.42 times the length of The Panama Canal, and the length of The Panama Canal is 2.4 times that amount.(Canal de Panamá) (Panama)
It's about one-third as long as The English Channel.
In other words, 509 leas is 0.348 times the length of The English Channel, and the length of The English Channel is 2.87 times that amount.(average width between Isle of Ushant and The Walde Lighthouse) (La Manche, Ärmelkanal, Mor Breizh, Mor Bretannek) (a.k.a. The Channel)
It's about one-third as long as The 405.
In other words, 509 leas is 0.3195 times the length of The 405, and the length of The 405 is 3.1299 times that amount.(a.k.a. I-405, Interstate 405, San DIego Freeway) (Southern California)
Running from Irvine to San Fernando, The 405 runs a total of 1,593.1 leas. The 405 is the most heavily-trafficed freeway in the United States, with an average speed as low as 8 kph during rush hours.
It's about three-tenths as long as Hadrian's Wall.
In other words, 509 leas is 0.31 times the length of Hadrian's Wall, and the length of Hadrian's Wall is 3.2 times that amount.(a.k.a. Roman Wall, a.k.a. The Wall, a.k.a. Vallo di Adriano, a.k.a. Vallum Aelium, a.k.a. Severus' Wall) (from North Tyneside, Tyne and Wear, England, United Kingdom to Cumbria, North West England, United Kingdom)
It's about three-and-a-half times as tall as Maxwell Montes.
In other words, the height of Maxwell Montes is 0.29 times 509 leas.(Ishtar Terra, Venus)
Maxwell Montes rises to a total height of 150 leas. Since Venus does not seem to have the kind of tectonic activity which gives rise to mountains on Earth, the origin of the Venusian mountain remains the subject of some dispute.
It's about three-and-a-half times as tall as The Challenger Deep (Marianas Trench).
In other words, 509 leas is 3.4154 times the height of The Challenger Deep (Marianas Trench), and the height of The Challenger Deep (Marianas Trench) is 0.29279 times that amount.(near Marianas Islands, a.k.a. Ladrones Islands, northwestern Pacific Ocean) (depth below sea level)