Oceans of the world


Do the oceans have borders?  We may determine the ocean borders by using land ( city or country) as beacons.


Approximate borders of the world’s oceans

Comparisons of the world’s biggest oceans:      

Body of Water                 

Area (106 km2)       

Volume (106 km3)                       

Mean Depth (m)

Atlantic Ocean                                




Pacific Ocean                                  




Indian Ocean                                   




All oceans and seas                        





The oceans around South Africa

  • The warm Mozambique-Agulhas Current skirts the east and south coasts as far as Cape Agulhas, while the cold Benguela Current flows northwards along the west coast as far as southern Angola.
  • The contrast in temperature between these two currents partly accounts for significant differences in climateand vegetation, as well as differences in marine life.
  • Owing to the cold waters of the west coast being much richer in oxygen, nitrates, phosphates and plankton than those of the east coast, the South African fishing industry is centred on the west coast. 
  • The 3 000-km coastline is an even, closed one with few bays or indentations naturally suitable for harbours.
  • Saldanha Bay on the west coast is the only ideal natural harbour, but the area lacks fresh water and does not offer natural lines of penetration to the interior.
  • The warmer East Coast makes for a popular tourist destination, even during the colder winter months

Oceans and Currents

Have you noticed something on the map above?

Yes, you are right- the ocean currents operate in huge circles or rotating currents, called gyres. 

gyre in oceanography is any large system of rotating ocean currents, particularly those involved with large wind movements.

There are five mayor (most notable) gyres:  Indian Ocean Gyre, North Atlantic Gyre, North Pacific Gyre, South Atlantic Gyre, South Pacific Gyre

Why is the Oceans Salty?

As water flows in rivers, it picks up small amounts of mineral salts from the rocks and soil of the river beds. This very-slightly salty water flows into the oceans and seas. The water in the oceans only leaves by evaporating (and the freezing of polar ice), but the salt remains dissolved in the ocean – it does not evaporate. So the remaining water gets saltier and saltier as time passes.


How Ocean Currents affect Climate

tropical cyclone is a rapidly-rotating storm system characterized by a low-pressure centre, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain.

Depending on its location and strength, a tropical cyclone is referred to by names such as hurricane, typhoon, tropical stormcyclonic stormtropical depression, and simply cyclone.

As they move from the ocean to the land, they cause lots of damage to property and lives.                     

Deadly cyclones in modern history: 

Katriena (USA) in 2008 in Louisiana and Mississippi and Sandy in eleven USA states in 2012 killed thousands of people.

The Phillipines also had some of the deadliest cyclones in recent years, one in December 2012.