The World's Largest Animals   The largest animal known to exist is the blue whale ( 110 feet long, 90 tons ). The largest living bird is the ostrich ( 8 feet tall, 300 lbs.)   The largest living land animal is the elephant ( 12 feet tall, 6 tons )   The tallest living animal is the giraffe ( 20 feet tall )   The World's Longest Rivers   The longest river in the world is the Nile River, which flows for 4,160 miles ( 6,695 km ), from the mountains of Central Africa to the Mediterranean Sea.  Three major rivers follow closely behind. They are the Amazon in South America at 4,000 miles ( 6,440 km)   The Yangtze Kiang ( Chang Jiang ) in China at 3915 miles ( 6,300 km ),   and the mighty Mississippi River in the USA at 3,740 miles ( 6,019 km ).		The World's Highest or Tallest Waterfalls   Angel Falls in Venezuela, with a drop of 3,212 ft. ( 979m ), is the world's tallest waterfall Tugela Falls ( 3,110 ft. ) in South Africa by only 102 ft The World's Largest Deserts   1.) Sahara Desert in North Africa 3,500,000 sq. miles ( 9,100,00 km ) 2.) Great Australian Desert 1,480,000 sq. miles ( 3,830,000 km ).   3.)Gobi Desert in Asia 500,000 sq. miles ( 1,295,000 km ).   The World's Highest Mountains   The world's four highest mountains are similar in height and are all located in the Himalayas of Asia. They are: 1.) Mount Everest at 29,028 ft. ( 8,848m ) 2.) K2, also known as Chogori, at 28,250 ft. ( 8,611m )   3.) Kangchenjunga at 28,165 ft.( 8,585m)   4.) Lhotse 1 at 27,890 ft ( 8,501m )