How big is the world's biggest iceberg? How deep can you dive without oxygen? Is the world's largest mountain range really under the sea? Let's get to the bottom of some pressing sea-faring questions with our ocean facts.



  • Earth has five major oceans which are made up of individual seas. The largest is The Pacific, located between the Southern Ocean, Asia, Australia and the western hemisphere, over an area about 15 times the size of the USA. It contains more than 25,000 islands.
  • The Challenger Deep is the lowest spot in all the world's oceans, located in The Pacific. To put its depth into perspective, if you dropped in Mount Everest (8,850 metres high), there'd still be more than a mile of ocean above it.


  • Australia's Great Barrier Reef covers an area bigger than Great Britain and can even be seen from space. The Reef is a collection of islands which are home to over 400 types of coral and among which live more than 2,000 species of fish and many more sea life.
  • The blue whale can grow up to 30 metres in length; the heart alone can be the size of a car. Not only is it the largest animal in the ocean, it is the largest animal to ever roam our planet. By the early 1960s blue whales were nearly extinct, but in 1966 whaling was banned and there are currently around 10,000 blue whales in existence.
Ocean Wave

Exploring the Ocean

  • Not for the fainthearted or weak-lunged, free-diving is deep-sea diving while holding your breath. In 1976, Jacques Mayol, 56, immortalised in Luc Besson's The Big Blue, dived 105 metres without breathing equipment.
  • Captain Matthew Webb was the first person to swim the English Channel; in 1875 he took 21 hours and 45 minutes. The fastest was Christof Wandratsch, who in 2005 crossed in seven hours, three minutes and 52 seconds. David Walliams eat your heart out.
  • Enjoy a spot of windsurfing on your summer holidays? Perhaps you wouldn't want to go as far as Brazilians Flavio Jardim and Diogo Guerreriro. In 2005 the record-holding pair travelled 5,045 miles along the Brazilian Coast.


  • The world's highest tides occur at the Bay of Fundy, which separates New Brunswick from Nova Scotia. In fact, at springtime, the difference between low and high tide can be 16.3 metres - about the height of a three storey building.
  • The Earth's longest mountain range is underwater. The Mid-Ocean Ridge runs around the globe from the Arctic to the Atlantic, via Africa, Asia and Australia. That's four times longer than the Andes, Rockies and the Himalayas combined.
  • The Arctic produces up to 50,000 icebergs – large chunks of ice that break away from glaciers and float in open sea – every year. They're classified by the International Ice Patrol as Growlers (the smallest bergs, just one metre tall) or Very Large (over 75 metres).