Oceans and seas

Observed from space, our planet’s surface appears to be dominated by the color blue. This blue color occurs because of the presence of the oceans and seas of the world. These features cover approximately 71% or 361 million square kilometers (139 million square miles) of Earth’s surface with a volume of about 1370 million cubic kilometers (329 million cubic miles). The average depth of these bodies of seawater is about 3.8 kilometers (2.4 miles). Maximum depths can exceed 10 kilometers (6.2 miles) in areas known as ocean trenches. The oceans contain 97% of our planet's available water. The ocean is also home to many forms of life uniquely adapted to survive in this habitat. Humans have degraded the oceans and their life through pollution, overfishing, carbon dioxide acidification and resource exploitation.

  • Indigo hamlet Featured Article Indigo hamlet Indigo hamlet

    The indigo hamlet (scientific name: Hypoplectrus indigo) is a member of the grouper/seabass family (Family Serranidae) that live on coral reefs in the Western Atlantic Ocean... More »

  • Spinner dolphin Featured Article Spinner dolphin Spinner dolphin

    The Spinner dolphin (Stenella longirostris), a marine mammal in the family of oceanic dolphins,  gets its name from the spinning behavior it shows when it leaps out of... More »

  • Ocean acidification troubles Featured Article Ocean acidification troubles Ocean acidification troubles

    The seas in which corals and other calcifying species dwell are turning acidic, their pH slowly dropping as Earth's oceans acidify in response to increased carbon dioxide... More »

  • Marine biodiversity Featured Article Marine biodiversity Marine biodiversity

    Biodiversity is now commonly defined as the variety of life in genes, species and habitats. According to the definition of the Convention on Biological Diversity, biodiversity is... More »

  • Coccolithophores Featured Article Coccolithophores Coccolithophores

      Like any other type of phytoplankton, coccolithophores are one-celled marine plants that live in large numbers throughout the upper layers of the ocean. Unlike any... More »

  • Long-finned pilot whale Featured Article Long-finned pilot whale Long-finned pilot whale

    The long-finned pilot whale (scientific name: Globicephala melas) is one of two species in the genus Globicephala. The pilot whale is so named because when swimming, the groups... More »

  • Seas of the world Featured Article Seas of the world Seas of the world

    A sea is commonly defined to be an extended body of saline water associated with one of the worlds five oceans (Atlantic, Indian, Pacific, Arctic, and Southern oceans). Some seas... More »

Recently Updated
Adriatic Sea Last Updated on 2015-09-29 15:00:08 The Adriatic Sea is a branch of the Mediterranean Sea lying between 2 (50,590 miles2). The Adriatic has a maximum depth of 1233 metres (m) and an average depth of 252 m; although north of a line from Zadar, Croatia to Pescara, Italy, it is less than 100 m deep. The northern end of the sea is the Gulf of Venice and its southern limit is the Strait of Ontranto. By European standards, the Adriatic is both warm (surface water temperature ranges from 8-13oC in winter to 22-25oC in summer) and low in turbidity; correspondingly, this sea is a  popular tourist destination. Map of the Adriatic Sea basin. Source: Norman Einstein/Wikimeia Commons True-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 18, 2002. Source: NASA The Adriatic coastline is heavily indented and includes many islands. As a result the coastline is... More »
Spratly Islands Last Updated on 2015-06-01 15:45:31 The Spratly Islands consist of more than 150 small islands or reefs scattered over a sea area of nearly 360,000 square kilometres in the South China Sea, about two-thirds of the way from southern Vietnam to the southern Philippines. The closest countries to the Spratly Islands are Malaysia, Vietnam, Brunei and the Philippines. Abundant in marine biodiversity, the Spratly Islands lie in rich fishing grounds and potential gas and oil deposits. (See Energy profile of South China Sea) These islands are strategically located near several primary strategic shipping lanes in the central South China Sea. There are no indigenous inhabitants. But there are scattered garrisons occupied by military personnel of several claimant states, notably the Philippines. They are claimed in their entirety by Taiwan, Vietnam and China, while portions are claimed by Malaysia and... More »
Madagascar mangroves Last Updated on 2015-05-27 11:30:24 WWF Terrestrial Ecoregions Collection Shielded from monsoon winds by the Central Highlands of Madagascar, Madagascar mangroves occupy a wide range of environmental and climatic conditions, and chiefly occur at the western coastline along the Mozambique Channel of the Indian Ocean. Although the ecoregion’s species richness is low, it is noteworthy in supporting certain endemic tree species; for example, thre are only 163 vertebrate taxa found in the entire ecoregion. The Madagascar mangroves are within the Mangroves biome of the Afrotropic Realm. These mangroves also shelter highly diverse mollusk and crustacean communities, while capturing sediment that threatens coral reefs and seagrass beds. Dugongs, birds and sea turtles utilise mangroves, as do the native Malagasy people. Rice farming, shrimp aquaculture as well as stockpiling of... More »
Marine biodiversity and food security Last Updated on 2015-02-28 19:05:44 Harvesting of wild fish and shellfish from the oceans provides food to the earth’s population, particularly in the developing world, and is a major contributor to the world economy. In the USA alone, fishing supports an industry worth nearly $50 billion annually. Although fishing commenced very early in human history, it was during the 20th century that its reach and impact spread around the globe and into deep waters, first with the advent of motorized vessels near the turn of the century, and later as a result of widespread availability of cheap oil, refrigeration, and increasingly effective technology. These developments made fishing an intensive global industry, particularly after Word War II. Modern fisheries, including both landings and by-catch, currently consume 24-35% of global marine primary production in the continental shelf and major upwelling areas,... More »
Deepwater Horizon Oil Spill: The Fate of the Oil Last Updated on 2015-02-02 17:02:07 Summary The April 20, 2010, explosion of the Deepwater Horizon offshore drilling rig led to the largest oil spill in U.S. waters. Federal government officials estimated that the deepwater well ultimately released (over 84 days) over 200 million gallons (or 4.9 million barrels) of crude oil. Although decreasing amounts of oil were observed on the ocean surface following the well’s containment on July 15, 2010, oil spill response officials and researchers have found oil in other places. A pressing question that has been raised by many stakeholders is where did the oil go? On August 4, 2010, the federal government released an estimate of the oil spill budget for the Deepwater Horizon incident. On November 23, 2010, the federal government released a peerreviewed “Technical Document” that further explained how the estimates were derived, and in some cases, modified the... More »