We classify ‘World Ocean’ into four parts i.e. Pacific Ocean, Atlantic Oceans, Indian Ocean and Arctic Ocean.
1. Pacific Ocean:
This is the largest ocean of the world. Its average depth is 4280 meters (14040 feet) or 2,333 fathoms. Its total area is 16,52,50,000 square kilometers which is 1/3 part of total area of Earth. Pacific Ocean covers 46% part of world Oceans. This Ocean is touched by five continents. At equator its extent is more than 16000 kilometers. Maximum typhoons and active volcanoes are found in this ocean.
It has triangular shape and Bearing Strait is situated in its north. Asia and Australia form its one part and other part is formed by North America and South America. Antarctic Ocean is situates towards its south. Size of Pacific Ocean is decreasing by 2-3 cms every year on the other hand the size of Atlantic Ocean is increasing.
Continental Slope of Pacific Ocean is quite broad along Asia, Indonesia and Western Coast of Australia. Its breadth extends from 100 meters 150 meters. Many islands are situated along the continental slope of Pacific Ocean e.g. Islands of Japan, Philippines, Indonesia and New Zealand. Its breadth becomes narrow along the western coast of America, where its average breadth is 100 meters.
Overall, more than 20,000 islands are situated in this Ocean. Islands situated in its north and continental slopes are formed by volcanic eruption. Mauna Kea and Mauna Loa are the major peaks situated on these islands, height of these peaks, is 4213 and 4168 meters respectively. In north its depth extends from 5000 meters to 6000 meters.
Various trenches are found in this ocean e.g. Aleutian, Kurile, Japan and Bonin. Most of the trenches are situated along the Islands. Celebes Sea, Coral Sea, East China Sea, Yellow Sea Tasman Sea etc. are situated towards its west coast. In the western part Malacca Straight connects the Pacific and Indian Ocean.
2. Atlantic Ocean:
The shape of Atlantic Ocean resembles with English language Roman Script alphabet ‘s’. It covers 22% part of the Earth and its average area is 8,24,00,000 square kilometers. Its average depth is 3,339 meters (10,955 feet) or 1826 fathoms than that which is less Pacific Ocean. Its deepest part is ‘Milwanke-deep’ (8380 meters) which is situated in the north of ‘Puerto Rico’.
Its breadth is 1530 nautical miles (between Brazil and Sierra Leone) and in south it is 3450 nautical miles or 6400 kilometers. The eastern side of this ocean is connected with North and South America and its eastern side is connected with Africa and Europe.
It is quite wide at eastern and western coasts and is situated along the coasts of America and Europe. The slope is quite narrow between South America and Africa while major broad continental slopes of the world are around New Foundland and British Isles. Grand Bank and Dogger Bank are situated here which are the most popular places of world for fishing. The breadth of continental shelf extends from 250 to 400 Kilometers near the coasts of North Eastern America and North Western Europe.
Mid Atlantic Ridge:
Deep ‘sea plains’ are found in this ocean, which do not have equal depth. Their elevation towards central part to eastern and western coasts is quite gentle and a long mountain has been formed in the centre which is like a ridge. This is the specialty of Atlantic Ocean floor. This mountain extends from Greenland to Bouvet Islands and vertically divides this Ocean into two parts.
Its average height is 14000 meters and it is 14000 kilometers long. Its large part is covered by water but some of its parts are visible above the sea in the form of islands. Some of these islands are Ascension Island, Tristan da, Cunha, Azares, St. Helena and Gough. These are all volcanic islands and their various small peaks attain the form of islands.
The upper line of this mountain is quite wide at 55° North latitude, which is known as Telegraphic Plateau. This is also known as under water rise. Various seas and bays are situated on its coast. On the western coast of ocean ‘Hudson Bay’ and ‘Basin Bay’ are situated and on the eastern coast ‘Northern Sea and Baltic Sea are situated.
This Ocean does not have large number of trenches. Around 19 trenches are 5500 meter deep at average and 2 trenches are 7000 meters deep in this Ocean. Many deep sea parts e.g. Labrador Basin, North Eastern Atlantic Ocean Basin, Argentina Basin and Agulhash Basin are part of Atlantic.
3. Indian Ocean:
Although this ocean is smaller than Pacific and Atlantic Oceans yet it is more important for us. It is situated in the south of our country and its name is also based on older name of our country. The total area of this ocean is 7,34,25,500 square kilometers and its average depth is 3960 meters. It is almost triangular in shape and is surrounded by Iran, Pakistan, India, Bangladesh, in north and north east, by Australia in the east, by Antarctica in the south and in west, by Africa.
Average width of its continental slope is 75 miles (120 km). It is 190 miles (1300 kms) wide near Mumbai, which is almost maximum. Tropic of cancer is the upper boundary of this Ocean and 90 percent part of this Ocean lies below the Equator i.e. in Southern hemisphere. Its bed is completely flat.
Red sea and Persian Gulf are situated in its North, Arabian Sea in North West, Andaman Sea and Bay of Bengal are situated in its North east. Trenches are very rare in this Ocean. Sunde trench is situated in the south of Java. Which is 8152 meters deep? There are many under Water Mountains, situated on the bed of Indian Ocean.
Longest mountain (Submarine Ridge) extends from Cape Comorin to southwards (Towards Antarctica). It is quite wide but it is not very high. It is wider than mid Atlantic Ridge. Its elevated (higher) parts are present in the form of islands e.g. Changes Mountain in its north, St. Paul Ridge and New Amsterdam ‘Medagaskar’ and ‘Sri Lanka’ are the largest islands of Indian Ocean.
4. Arctic Ocean:
Its size and depth is less as compared to other oceans. Actually it is circular and surrounds the North Pole. Its average size is 1,40,56,000 Sq. Kms. and its Coast line is 45390 kilometers. The Arctic Ocean is surrounded by Eurasia, North America, Greenland and various islands.
Various islands are found in this ocean namely, New Siberian Islands near Canada, Navaea and Jalmaya are major islands while. Barents Sea, Beaufort Sea, Chukchi Sea, East Siberia Sea, Green Land Sea, Kara Sea, White Sea, Hudson Bay and Baffin Bay are also found in this ocean.
It is connected with Pacific Ocean by Baring Straight and connected with Atlantic Ocean with the help of Greenland Sea and Labrador Sea. Its long submarine Ridge is known as Lomnosone Ridge.
The layer of ice of this Ocean is melting continuously slow pace and there is a possibility that major changes to occur by 2040.