Geography & Places
Why Is the Dead Sea So Salty?
The Dead Sea is so salty because water leaves only by evaporation, leaving the salt behind. See how salty it is, why people float and why its level is falling.
Video explainers
Short, narrated answers with maps, timelines and charts. Every video comes with a full article and its sources.
Geography & Places
What Is the Tallest Mountain in the World?
Everest is the highest mountain above sea level at 8,848.86 m, but Mauna Kea is taller from base to peak and Chimborazo's top is farthest from Earth's centre.
History
How Long Is the Great Wall of China?
The Great Wall of China is 21,196.18 km long, according to China's official survey of walls from all periods. The Ming dynasty wall alone is 8,851.8 km.
Geography & Places
What Is the Smallest Country in the World?
Vatican City is the world's smallest country: 0.44 km² (about 109 acres) and 882 residents. Learn how it became a state in 1929 and which countries come next.