10 of the tributaries flowing into the Amazon river are as big as the Mississippi river.
41
There's a lake under Antarctica that is 25 million years old called Lake Vostok.
109
The state with the longest coastline in the Continental U.S. is Michigan.
31
An earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.
243
The 'King Ranch' in Texas is bigger than the state of Rhode Island.
49
The longest cave in the world is the 'Mammoth Cave System' in the USA at 560,000 mtrs deep!
63