This ocean path is the longest straight road on Earth

Mindy Sparks
May 2, 2018

In 2012, Reddit user kepleronlyknows posted a map on Reddit that he claimed was the longest straight line you could trace across Earth's oceans: a trek of nearly 20,000 miles (32,186 km) in a straight line from Pakistan to the Kamchatka Peninsula, Russia. This took the computer longer, almost 45 minutes, yet it eventually uncovered an 11,241-kilometer path crosswise over 15 distinct nations, beginning near Quanzhou in eastern China, goes through Mongolia Kazakhstan and Russian Federation, and comes to the other end in the town of Sagres in western Portugal.

The longest ocean path to traverse the Earth is a sailable route that connects Pakistan to Russian Federation.

R. Chabukswar et al.

Thanks to Rohan Chabukswar of the United Technologies Research Center in Ireland, and Kushal Mukherjee of IBM Research in India, we finally have an answer. Their model processed data from the National Oceanic and Atmospheric Administration's ETOPO1 Global Relief model of Earth's surface. Because the data don't show details smaller than 1.8 square kilometers, the model could be missing tiny bodies of water that might appear on the China-to-Portugal path, Chabukswar says. Since the model also includes altitude data, the two can relatively determine which points are on land and which are at sea. Since each great circle in the model contains 21,600 points on either land or sea, this gives a total of five billion points to verify. Great circles always traverse the maximum circumference of the sphere, and thus always lie in the same plane as the center of the sphere. If that is hard to visualize, the equator is one of Earth's great circles.

The most challenging part of the study was optimizing the plotted routes. This shows our planet at a spatial resolution of about 1.8 kms.

Instead, they took another tack, as Science reports, using an optimization algorithm known as "branch and bound".


Initially, the researchers tried to brute force the answer by examining every possible great circle on the planet. With each iteration, the search for the optimal paths is fine-tuned.

Using their algorithm, it only took about 10 minutes of computing time on a laptop, the researchers say. It then fine tunes the search over and over again for lines that seem promising-those with the longest paths. The ship once set from Pakistan will not hit any land for about 32,090 kilometres until it reaches the Kamchatka Peninsula in Russian Federation. The sailing route begins in Sonmiani, Pakistan, passes through the gap between Madagascar and continental Africa, continues between Antarctica and Tierra del Fuego in South America, and finally reaches north-northwest across the Pacific, eluding the Alaskan archipelago, until it comes to an end on the beaches of the Karaginsky District, in Russian Kamchatka.

When the algorithm was run with the parameters in reverse, it produced the longest straight path on land.

"T$3 he path [originates] near Jinjiang, Quanzhou, Fujian, China, weaving through China and Mongolia for a bit, passing though Kazakhstan and Russian Federation to further weave through Belarus and Ukraine, and passing through Poland, Czech Republic, Germany, Austria, Liechtenstein, Switzerland, France, and Spain, to end near Sagres, Portugal, traversing a total of 15 countries".

That long haul covers 11,241.1 kilometres (6,984.9 miles), but before you start filling up your gas tank, you may want to bear in mind the researchers' final piece of travel advice. When the results came back, Anderson and his Wikipedia muse were proven correct, the team reported last week on the preprint server arXiv.

Other reports by Iphone Fresh

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