Derinkuyu in Turkey is an ancient underground city that could shelter up to 20,000 people along with livestock.

The Ring of Fire surrounds much of the Pacific Ocean.

The deepest lake in the world is Lake Baikal in Russia — it reaches a depth of over 5,300 feet.

The Maldives is the world's lowest-lying country, with an average ground level of just 1.5 meters above sea level.

The Great Rift Valley in Africa may eventually split the continent in two, forming a new ocean in millions of years.

The shortest commercial flight in the world is between two Scottish islands — it lasts about 90 seconds.

There are caves on Earth so deep they have their own weather systems.

Countries with extremely high tax rates sometimes collect less revenue than countries with moderate tax rates.

The Mediterranean Sea connects Europe, Asia, and Africa.