Vast in scope and size, there is only one true ocean on Earth. This connected body of water surrounds the continents and is divided into five major regions: the Pacific, Atlantic, Indian, Arctic, and Southern oceans. Taken together, the oceans cover more than 70 percent of the Earth's surface and give the planet the appearance, from space, of a blue marble.
The deep waters of these oceans hide from view rugged mountains, vast plateaus, active volcanoes, and seemingly bottomless trenches. These underwater landscapes are in an endless cycle of construction and destruction as new crust is born along mid-ocean ridges, pushing old crust into the depths of the fiery mantle.
The oceans appeared hundreds of millions of years ago as planet Earth cooled from its wild and hot adolescence. Layers of rock piled together and the vast amounts of steam that volcanoes spewed into the atmosphere turned to water vapor, condensed, and fell as rain. And rain it did. For thousands of years, the rains fell hard and filled giant depressions—forming the world's first seas.
Continental crust is less dense and thicker than the surface of the deep ocean. The transition from land to sea begins at the continental shelf, a gently sloping, submerged extension of the continent. The shelf ends at a break, where the increased steepness is defined as the continental slope. The slope leads down to the ocean abyss and its plains, plateaus, mountains, ridges, and trenches—hidden from view except for the tops of certain features that rise above the water's surface as islands.
The oldest rocks in the ocean date back only 200 million years, quite young for a planet thought to be about 4.5 billion years old. New crust constantly rises to the ocean surface along the mid-ocean ridge system, a giant underwater mountain range that snakes through the oceans like the stitching on a baseball. The birth of new crust pushes apart pieces of Earth's crust, called plates.
The pushing forces the old oceanic crust on the plate margins to bump into the edges of other plates. Where it collides with continental crust, the denser ocean crust dives beneath in a process called subduction. Once deep in the mantle, the crust melts into magma only to be spewed back to the surface along a mid-ocean ridge or an isolated volcano.
Subduction zones are marked by deep trenches, and just beyond them island arcs like Japan and mountains like the Andes in South America often rise. Where pieces of ocean crust collide, especially deep trenches form. (National Geographic.com)
Top Ten Ocean Facts (National Geographic Kids)
1. Around 70% of the Earth's surface is covered by oceans.
2. The largest ocean on Earth is the Pacific Ocean, covering around 30% of the Earth's surface.
3. The name 'Pacific Ocean' comes from the Latin name Tepre Pacificum, 'peaceful sea'.
4. The deepest known area of the Earth's oceans is known as the Mariana Trench. It's deepest point measures 11km.
5. The world’s oceans are home to incredible creatures that are masters of disguise.
6. The longest mountain range in the world is found under water. Stretching over 56,000km, the Mid-Oceanic Ridge is a mountain chain that runs along the center of the ocean basins.
7. About 70% of the oxygen we breathe is produced by the oceans.
8. The sea is home to the world’s largest living structure - the Great Barrier Reef. Measuring around 2,600km, it can even be seen from the Moon.
9. We have only explored about 5% of the world’s oceans. There’s a lot more to be discovered.
10. The sea can be described as the planet's mega museum. There are more artifacts and remnants of history in the ocean than in all of the world’s museums combined.
There are fiveoceans covering the surface of our globe: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Arctic Ocean, & the Southern Ocean.
Pacific Ocean Facts: The Pacific Ocean is the biggest ocean of the world and covers more than 30% of the Earth's surface. The name 'Pacific' come from the Latin word 'pacificus' which means peaceful. Thus, Pacific Ocean means 'peaceful ocean'. However, the Pacific is not really calm and peaceful. The 'ring of fire' is located in the Pacific Ocean. There is a string of volcanoes in the Pacific basin, which are still active, and therefore many of the world's major earthquakes and volcanic eruptions happen in this region.The lowest known point on earth is called Challenger Deep.It is located in the Pacific Ocean near Guam in the Philippine Sea at the end of the Mariana Trench. The depth recorded is 10,920m or 35,827 feet. The largest coral reef in the world is located off the Australian coast and is called the Great Barrier Reef.
Atlantic Ocean Facts: The Atlantic is the second biggest ocean in the world and is between the continents of America and Europe and Africa. The Atlantic Ocean is about half the size of the Pacific Ocean and covers roughly 20% of the Earth's surface. However it is growing in size as it is spreading along the Mid-Atlantic Coasts. The Mid-Atlantic Ridge is the longest mountain range on Earth, longer than the Rockies, Himalaya & Andes mountains combined. It spreads from Iceland to Antarctica beneath the Atlantic.
Indian Ocean Facts: The Indian Ocean is located between Africa and Austral-Asia. The waters of the Indian Ocean provides the largest breeding grounds of the world for humpback whales. Also found in the Indian Ocean is a fish, which was thought to be extinct: the Coelacanth is found in the warm waters off the Comoro islands between Mozambique and Madagascar. The Northern Indian Ocean also is the most important transport route for oil as it connects the oil-rich countries of the Middle East with the rest of the world. Every day tankers are carrying a cargo of 17 million barrels of crude oil from the Persian Gulf on its waters.
Arctic Ocean Facts: The Arctic Ocean is located around the North Pole across the Arctic Circle. A jellyfish with the funny name 'Lion's Mane Jellyfish' can also be found in the Arctic Ocean's waters. It grows up to 2.4m or 8 feet across and lives on plankton and fishes. The Arctic Ocean's ice covers are shrinking by 8% every ten years. Many Arctic ground features are named after early Arctic explorers, like Nansen Basin or Mendeleyev Ridge.
Southern Ocean Facts: The Southern Ocean is located around the South Pole across the Antarctic Circle in the Southern Hemisphere off Antarctica. The Southern Ocean is the home of Emperor Penguins, Elephant Seals, Wandering Albatrosses, and lots of icebergs. The Southern Ocean is also referred to as the Antarctic Ocean, South Polar Ocean or Austral Ocean. The Southern Ocean is the youngest ocean as it was formed 'only' 30 million years ago when South America and Antarctica moved apart.
80% of the world’s population lives within 500 miles of an ocean; 44% live in coastal areas. In 2016, the world’s population was estimated at 7.4 billion people.
Global warming may cause sea levels to rise from .5 to 1.4 meters (1.6 to 4.6 feet) by the end of this century.
In the United States in 2010, 123 million people (39% of the nation’s population) lived in counties directly on the shoreline.
We know of over 200,000 species of marine life – which is a pretty ridiculous number on its own – but estimates say that for every species of marine life already discovered, there are 2 or 3 more that we know absolutely nothing about.
Ocean life is estimated to have started as early as 3.4 billion years ago, vs. the 400 million years estimated for land dwellers.
Not only is coral being used as material for bone grafts in humans, but bio-medical studies have revealed that coral can play a vital role in bone healing as well. Coral reefs and their inhabitants are being used and studied for medical uses such as cancer treatment, painkillers, antiviral treatments and more.
Ghost Gear - Abandoned, lost and discarded nets, lines and traps are one of the biggest threats to our sea life. A staggering 640,000 tons of gear is left in our oceans each year. That gear traps, injures, mutilates and kills hundreds of thousands of whales, dolphins, sharks, seals, turtles and birds annually. (worldanimalprotection.us.org)
There may be more than three million shipwrecks on the ocean floor but only one percent has been discovered. These shipwrecks are often frozen in time, deep beneath the sea, waiting for scientists and archaeologists to explore and study. Watch Shipwrecked http://oceantoday.noaa.gov/every-full-moon/episode5-shipwrecked/welcome.html
Every year, 28-billion pounds of plastic end up in our oceans. (oceanconservancy.org) Deadliest ocean trash: 1. Fishing gear; 2. Plastic bags & utensils; 3. Balloons; 4. Cigarette butts; 5. Bottle caps