Where the Continents Come Apart

The Continents category itself: seven entities in this atlas, but "seven" is only one of at least four models taught around the world.

Asia: joined to Europe along one continuous landmass, Eurasia, with no physical break; Russian, Eastern European and Japanese curricula teach the two as a single continent.

Europe: its own highest point depends on whether the Caucasus counts as European (Mount Elbrus) or not (Mont Blanc), and its eastern edge along the Urals is a drawn line, not a physical one.

North America: joined to South America by the Isthmus of Panama; six-continent and Olympic five-continent models, common across Latin America and much of Southern and Western Europe, count the two Americas as one.

South America: the same Americas-combined argument, run from the southern side of the isthmus.

Australia: is the continent the mainland alone, or the wider Sahul-shelf region including New Guinea, or wider Oceania still? Three live open questions on this entity ask exactly that, down to whether submerged Zealandia counts as an eighth continent.

Antarctica: no sovereign states of its own; its "country count" instead means the thirty parties to the Antarctic Treaty System, a genuinely different kind of count from every other continent's.

Below the continent line, the seams keep going: Western Europe's own boundary shifted with the Cold War and shifted back after 1989.

Sub-Saharan Africa: bounded by the Sahara rather than by any national border, and counted at anywhere from 46 to 49 countries depending on which institution is counting.

Polynesia: a region defined not by a border at all but by a triangle drawn between three islands thousands of kilometers apart.