Geography & data
How One Line Earth maps the world
Every score in One Line Earth comes from a real map of the world. This page explains which map that is, how a line is judged to cross a country, and where the continents, oceans, seas, islands and facts in the atlas come from.
The map
The globe is drawn from Natural Earth’s 1:50 million scale country borders, a public-domain world map, through the World Atlas 2 project. It has 240 places: the world’s countries plus separately mapped territories. At this scale, coastlines and borders are generalised, and some very small islands and microstates do not appear.
Distances are measured over a spherical Earth with a mean radius of 6,371.0088 km.
How a line crosses a country
- A line is the shortest route between its two ends over the sphere, a great circle. That is why it looks curved on flat maps.
- Crossings are calculated exactly, by intersecting the line with each border on the sphere, not by sampling points along the way.
- A place counts once if the line touches it at all, including touching a border.
- Territories that the map draws separately count on their own. Antarctica is drawn and can be crossed, but it never counts.
Continents
Seven continents: Africa, Antarctica, Asia, Europe, North America, Oceania and South America. They follow the United Nations M49 regions, split where the conventional boundaries run: along the Ural Mountains and the Ural River, the Suez Canal and the Bosporus. Antarctica is Natural Earth’s Antarctica.
Oceans and seas
Five oceans: Pacific, Atlantic, Indian, Southern and Arctic.
Twelve major seas: Mediterranean, Caribbean, Black, Red, Baltic, North, Arabian, South China, Philippine, Bering, Coral and Tasman.
- The outlines come from Natural Earth’s marine areas.
- A sea or ocean counts as a discovery on your line once the line spends one unbroken stretch of at least 50 km in it. A sea takes precedence over the ocean around it.
- Straits, and waters whose ocean is disputed (such as the seas of the Indonesian archipelago), are left unclassified rather than guessed.
- In Explore Earth, the Atlantic and Pacific are split at the equator into north and south, and the Bay of Bengal can be selected on its own. These count towards their whole ocean in your saved discoveries.
Where one continent, ocean or sea ends and the next begins is a matter of convention. One Line Earth uses one documented set of conventions and applies it the same way everywhere.
Major islands
Explore Earth and your line results recognise 41 major islands. Each island is part of the same country map used for scoring, so the two always agree, and each was checked against its published area. A line discovers an island after one unbroken stretch of 20 km over it.
UN regions
Each country and territory is placed in one of 22 United Nations M49 sub-regions, such as Northern Africa, Eastern Europe or South-eastern Asia. In Africa south of the Sahara and in Latin America, the UN’s more specific intermediate regions are used (for example Eastern Africa or Central America). The few mapped places that the M49 list does not include separately are given the sub-region of the area they lie in.
Facts, depths and links
- Country facts such as capitals and areas are adapted from the open mledoze/countries dataset.
- “Did you know?” facts are written in our own words, each with a link to its source, mostly Wikipedia.
- Sea and ocean depths are taken from each water body’s Wikipedia article and linked. Where that article gives no figure, none is shown.
- Read more: 195 places link to their Countries.World profile and the other 45 to their English Wikipedia article.
Sources and licences
- Borders, land and marine areas: Natural Earth (public domain), via World Atlas 2.
- Country facts: mledoze/countries, under the Open Database License 1.0.
- Regions: UN M49 standard.
- Typeface: Space Grotesk, under the SIL Open Font License.