Of the seven great geographic lines, this is the only one that crosses no country. Not a short stretch of one, not a disputed sliver. None. Run the border data against it and the single result is Antarctica, which belongs to nobody.
That alone makes it worth a map. The Antarctic Circle marks the northern limit of the southern midnight sun: on it, the sun stays up all day at the December solstice and doesn't rise at all in June. Below it, those periods lengthen until you reach the pole and get six months of each.
Most of its 15,986 km is open water, the roughest open water on the planet. The circle runs through the Southern Ocean for roughly nine tenths of its length, crossing the Drake Passage, the Weddell Sea approaches and the long southern reaches of the Indian and Pacific Oceans before touching ice.
Worked out by intersecting the line with national borders, so the order is the order you’d meet them tracing the line west to east. Tap any row to fly the map to that crossing.
| # | Country | Enters and leaves | Distance |
|---|---|---|---|
| — | not a country | 1,230 km |
Latitudes here use the J2000.0 axial tilt of 23.4394°. The 2026 figure is nearer 23.4359°, which puts the real line about 390 m nearer the pole than the coordinates above, and it keeps shifting by roughly 14.5 m a year. No crossing changes hands over that distance.
The crossings in the table are coastline segments of Antarctica, not countries. The first is the Antarctic Peninsula, where the circle cuts across the Graham Land coast at around 65°W. Britain's Rothera station on Adelaide Island sits at 67.57°S, roughly 110 km south of the line, which is why Rothera gets a proper polar night and the stations further up the peninsula don't.
Then there's the long haul east. The circle clips Enderby Land, runs offshore past most of Queen Maud Land, then catches successive pieces of the Wilkes Land and Queen Mary Land coasts where the continental margin pushes north of 66.56°S. Those stretches are where the table's land figures come from.
Everything in between is ice shelf, sea ice or ocean, and the distinction between those three moves with the season. Sea ice around Antarctica roughly quintuples in area between February and September, from around 3 million km² to 18 million. For half the year a ship can reach the circle in several places; for the other half it can't reach it anywhere.
Seven countries claim territory in Antarctica: Argentina, Australia, Chile, France, New Zealand, Norway and the United Kingdom. Several of those claims overlap, most of the world doesn't recognise any of them, and the Antarctic Treaty of 1959 froze all of them in place. Article IV says nothing done while the treaty is in force counts as asserting, supporting or denying a claim.
So the honest answer to the question is zero, and the table reflects that rather than fudging it with claim boundaries. The circle does pass through the longitudes of the Australian, Norwegian, French and British claims, and through the overlapping Argentine, Chilean and British sectors on the Peninsula. None of that makes them countries.
The treaty has 58 parties and has held since 1961, which for a continent that size with no police force and a great deal of unexploited geology under the ice is a reasonable record.
Crossing the Antarctic Circle is a thing cruise passengers collect, and the usual Antarctic voyage never gets near it. The standard Antarctic Peninsula trip out of Ushuaia turns around somewhere around 64 to 65°S, a couple of hundred kilometres short. Ships that do cross advertise it specifically and charge accordingly.
The other misconception is that the circle marks where it gets cold. It doesn't, particularly. The Peninsula at 66°S has summer temperatures around freezing and supports moss, lichen and two flowering plants. The South Pole, 2,600 km further on and 2,800 m up, averages around −49°C. Altitude and the shape of the ice sheet matter far more than latitude down here.
And like the Arctic Circle, this one is on the move, drifting south by roughly 14.5 metres a year as the Earth's axial tilt reduces. Nobody has built a monument on it to go wrong, which is one problem Antarctica doesn't have.
The line of latitude 66.5606°S is intersected with the Natural Earth 1:110 million borders in the same way as every other line on this site, and the result comes back with a single entry. That's the finding, not a gap in the data.
Antarctic coastlines deserve a heavier caveat than anywhere else, though. The 1:110m outline follows the ice edge rather than the rock, and the ice edge moves: shelves advance, calve and retreat on timescales of years. The land figures here should be read as the right order of magnitude and nothing finer. The ocean fraction, around 90%, is solid.