The longest cave in the world is the 'Mammoth Cave System' in the USA at 560,000 mtrs deep!
63
The Dallas/Ft. Worth airport is larger than New York City's Manhattan Island.
62
Venice Island was built on a foundation of tree trunks. 1200 years later, those same trunks still support almost all of central Venice.
8
It takes a drop of ocean water more than 1,000 years to circulate around the world.
61
The city of Houston, Texas is built on a swamp and is slowly sinking!
89
10 of the tributaries flowing into the Amazon river are as big as the Mississippi river.
41