Our oceans and seas are a mysterious place, where we have only just scratched the surface of what we know about the watery world. Below are some interesting facts about the oceans that you may not have known. Who knows what else we will discover in the depths of the ocean as we continue our study and exploration into the depths of the watery abyss? 


The world’s five oceans account for more than two thirds of the Earth’s surface. Within them 97 per cent of the world’s water is found. Ocean currents wrap around the globe. These currents act like channels, which allow water to move from one part of the world to another. Currents bring nutrients from the ocean depths to the surface, providing a vital link in the food chain of all marine life. 

OceanCredit: morguefile


Unlike waves which come and go depending on the weather, but the tides are constant. On every beach across the globe the tide will go in and out every day. Tides are caused by the gravitational pull of the moon. The moon’s gravity pulls the ocean water towards it. That means that the beaches on Earth that are facing the moon will have high tides, while on the other side of the Earth it will be low tide. In some places the difference between high tide and low tide can be small, in other parts the water can recede several kilometres.

Tsunamis: Mega Waves

The word tsunami comes from a Japanese word meaning ‘harbour wave’. Tsunamis are mega waves that are huge and destructive. They are caused by movement in the tectonic plates, or underwater earthquakes or volcanoes. Reaching speeds of up to 800 kilometres per hour, while they travel the open ocean tsunamis barely make a ripple on the surface of the water. However, once they reach the shallow water of a coastline, their incredible energy is unleashed. When a tsunami hits the shore, the water is forced upwards as it gets closer to land, creating a giant wave that can be taller than a skyscraper when it arrives at the beach. 

Twenty Facts About the Ocean

  1. Biologists estimate between 500,000 and five million marine species have yet to be discovered and described.
  2. If all the salt in the oceans was taken out and dried, it would cover the continents to a depth of 1.53 metres.
  3. 90 per cent of all volcanic activity occurs in the oceans. In 1993, scientists located the largest known concentration of active volcanoes on the sea floor in the south pacific. This area, about 140,000 square kilometres, is home to 1133 volcanic cones and sea mounts.
  4. The Mid-Ocean Ridge underwater mountain range winds 74,000 kilometres from the Arctic Ocean to the Atlantic, skimming the coasts of Africa, Asia and Australia, before crossing the Pacific to the west coast of North America. It is more than four times the length of the Andes, Rockies and Himalayans combined.
  5. The oceans cover 71 per cent of the Earth and contain 97 per cent of its water. Less than 1 per cent of Earth’s water is actually fresh and 2-3 per cent is frozen in glaciers and ice caps.
  6. The average depth of the ocean is around 4 kilometres. The deepest point lies off the coast of Japan in the Mariana Trench, 10.9 kilometres down.
  7. At 4C (40F), the average temperature of almost the entire deep ocean hovers around freezing.
  8. The highest tides in the world are at the Bay of Fundy which separates New Brunswick from Nova Scotia, Canada. At some times in the year the difference between high and low tide is 16.5 metres, the equivalent of a three storey high building.
  9. Canada has the longest coastline of any country, at 90,850 kilometres, which equals around 15 per cent of the world’s 599,294 kilometres of coastline.
  10. Although Mt Everest, at 8848 metres, is often called the tallest mountain on Earth, Mauna Kea, an inactive volcano on the island of Hawaii, is actually taller. Only 4205 metres (13,700 feet) of Mount Kea stands above sea level, yet it is 10,200 metres (33,474 feet) tall if measured from the ocean floor to its summit.
  11. Water pressure at the deepest point in the ocean is more than 8 tons per square inch, the equivalent of one person trying to hold up 50 jumbo jets.
  12. The Gulf Stream in the Atlantic Ocean flows at a rate nearly 300 times faster than the Amazon River, the world's largest river.
  13. Coral reefs only make up less than 0.5 per cent of the ocean floor; however it is estimated that more than 90 per cent of marine life are directly or indirectly dependent on them.
  14. There are about 4,000 coral reef fish species worldwide, which accounts for roughly 25 per cent of all marine fish species.
  15. Less than 10 per cent of the ocean has been explored by humans.
  16. Until 2000, the Sothern Ocean was not officially recognised, but joined the Pacific, Atlantic, Indian and Arctic after a decision by the International Hydrographic Organistation.
  17. A tsunami travels faster than a jumbo jet. The freak waves can travel for thousands of kilometres and are able to cross from one side of the Pacific Ocean to the other in less than a day.
  18. The Dead Sea was given that name because no fish live in it. It lies between Israel and Jordan and is actually a lake. It holds the world’s saltiest water, which is roughly six times saltier that the ocean. The least salty part of the ocean is found in the Atlantic off the coast of South America, where millions of litres of fresh water flow daily from the Amazon River.
  19. The Pacific Ocean is large and deep enough to swallow every continent.
  20. Less than 0,5 per cent of marine habitats are protected by law, compared with 11.5 per cent of animal habitats that are protected on the land.