Longest Straight Line Paths on Water or Land on the Earth (2018)
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A branch-and-bound algorithm finds the longest straight-line path on water or land on Earth.
The paper presents a method using the branch-and-bound algorithm to find the longest great-circle path that stays entirely on water or entirely on land. The longest sea path runs from Pakistan to Russia, covering about 80% of Earth's circumference. The longest land path runs from Portugal to China, covering about 28% of the circumference.
The authors note the problem is complicated by islands, lakes, and the fractal nature of coastlines. They confirm a Reddit user's earlier claim about the sea path.
What commenters are saying
Commenters confirm the paper validates a Reddit user's earlier finding. One comment notes the Reddit user initially used a string on a globe. Several comments critique the 'drivable' land path as impassable due to the Alps.
A counter-claim emerges: a longer land path exists from Senegal to China, but the paper's treatment of below-sea-level areas as water excludes it. Another commenter notes the sea path passes through the Drake Passage, not the Beagle Channel.