It's about eleven times as long as Hadrian's Wall.
In other words, the length of Hadrian's Wall is 0.091 times 786.50 miles.(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)
Hadrian's Wall, which crossed England form the North Sea to the Irish Sea during the time of Roman rule, measures 75 miles (about 79 Roman miles). Roman soldiers — at one time up to 10,000 of them — only occupied Great Britain for about 246 years after the wall was built, after which time the local Brits began to take residence the wall's garrisons.
It's about twelve times as long as The English Channel.
In other words, 786.50 miles is 11.80 times the length of The English Channel, and the length of The English Channel is 0.0847 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)
The English Channel measures between 66.50 miles, narrowing as it flows northeast. The world speed record for a Channel crossing by swimmer was set by Australian Trent Grimsey in 2012, with a time of 6 hours, 55 minutes.
It's about fourteen times as long as The Panama Canal.
In other words, the length of The Panama Canal is 0.071 times 786.50 miles.(Canal de Panamá) (Panama)
Connecting the Atlantic and Pacific Oceans across the Isthmus of Panama, the Canal measures 55 miles in length. Ships passing through the Canal are raised (and then lowered) 0.016 miles above sea level through the lock-and-dam system.
It's about one-thirtieth as long as The Circumfrence of Earth.
In other words, 786.50 miles is 0.031584494 times the length of The Circumfrence of Earth, and the length of The Circumfrence of Earth is 31.6611060 times that amount.(Equatorial)
The Earth — not a perfect sphere, but rather an oblate spheroid with bulged middle — has an Equatorial circumference of approximately 24,901.4590 miles. The first airplane trip around the circumference of the Earth (with a few stops along the way), was completed in 1924 by the United States Army Air Service, and took 175 days.
It's about 45 times as tall as Olympus Mons.
In other words, the height of Olympus Mons is 0.021 times 786.50 miles.(a.k.a. Mount Olympus) (Mars)
The tallest mountain in the solar system, Olympus Mons rises to approximately 17 miles. The mountain has been known to astronomers since the nineteenth century because it is tall enough to rise above Mars' frequent dust storms.
It's about 100 times as tall as The Challenger Deep (Marianas Trench).
In other words, 786.50 miles is 116.10 times the height of The Challenger Deep (Marianas Trench), and the height of The Challenger Deep (Marianas Trench) is 0.0086133 times that amount.(near Marianas Islands, a.k.a. Ladrones Islands, northwestern Pacific Ocean) (depth below sea level)
The Challenger Deep, at the southern end of the Marianas Trench, reaches a depth of 6.77420 miles below sea level. There has been only one manned expedition to the bottom of Challenger Deep — a 1960 voyage that took 4 hours and 48 minutes to reach the bottom.
It's about 100 times as tall as Maxwell Montes.
In other words, 786.50 miles is 120 times the height of Maxwell Montes, and the height of Maxwell Montes is 0.0083 times that amount.(Ishtar Terra, Venus)
Maxwell Montes rises to a total height of 6.80 miles. 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.