Superlatives: the most and the least
Most superlatives come with an argument attached, usually about the definition rather than the measurement. These are the ones where the argument is the interesting half.
Which country has the longest coastline in the world?
Canada
Canada's coastline is about 202,000 km, more than the next several countries put together, because of the enormous fractal fringe of the Arctic archipelago. Indonesia, second, is about 55,000 km.
Source: CIA World Factbook coastline figures
How big is Vatican City?
About half a square kilometre
Vatican City is about 0.49 km2. You could walk its entire perimeter, roughly 3.4 km, in under an hour. It is the smallest sovereign state in the world by both area and population.
Source: Holy See official figures
Some weather stations in the Atacama Desert have recorded what?
No rainfall for a whole year
Parts of the Atacama average close to 1 mm of rain a year, and some stations have gone years with no measurable rainfall. A rain shadow from the Andes plus a cold offshore current keeps moisture out.
Source: Chilean Meteorological Directorate station records
Lake Baikal holds roughly what share of the world's unfrozen fresh surface water?
About a fifth
Baikal is about 1,642 m deep and holds around 23,600 km3 of water, roughly 20 percent of all unfrozen fresh water on the surface of the planet. That is more than all five North American Great Lakes combined.
Source: UNESCO World Heritage listing for Lake Baikal
Which is the highest capital city in the world?
La Paz, Bolivia
La Paz sits at roughly 3,640 m, and its administrative districts climb past 4,000 m. Quito is about 2,850 m and Bogotá about 2,640 m.
Source: Elevations from Bolivian and Ecuadorian national statistics
Which country has the most islands?
Sweden, with over 260,000
Sweden counts about 267,000 islands, most of them tiny uninhabited rocks in its lakes and archipelagos. Indonesia's 17,000-odd islands are far larger and far more populated.
Source: Statistics Sweden island count
What is the largest desert on Earth?
Antarctica
A desert is defined by precipitation, not heat. Antarctica gets very little (parts of the interior average under 50 mm a year), and at about 14 million km2 it is comfortably larger than the Sahara's 9.2 million.
Source: Standard climatological definition; areas from the British Antarctic Survey