The Congo River is the only major river that crosses the equator twice.

The Earth's continents were once joined as Pangaea.

The city of Jericho is one of the oldest known walled cities.

There is more water in Earth's mantle than in all the oceans on the surface.

The Nile Delta is one of the world's largest river deltas.

The world's deepest lake is Lake Baikal in Russia, containing 20% of the world's unfrozen fresh water.

The shortest commercial flight in the world operates between two Scottish islands — Westray to Papa Westray — lasting about 90 seconds.

Antarctica is technically a desert — it receives less precipitation than the Sahara in many areas.

The first forests appeared during the Devonian period.