The oceans are, by far, the largest storehouse of water on earth — over 96% of all of Earth's water exists in the oceans. Not only do the oceans provide evaporated water to the water cycle, they also allow water to move all around the globe as ocean currents.
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Water cycle components » Atmosphere · Condensation · Evaporation · Evapotranspiration · Freshwater lakes and rivers · Groundwater flow · Groundwater storage · Ice and snow · Infiltration · Oceans · Precipitation · Snowmelt · Springs · Streamflow · Sublimation · Surface runoff
The ocean is a huge storehouse of water
When we talk about the water cycle, we must consider both where water is stored in pools, and the fluctuation of water between those storehouses. Much more water is "in storage" for long periods of time than is actively moving through the cycle. It is estimated that of the 332,500,000 cubic miles (mi3) (1,386,000,000 cubic kilometers (km3)) of the world's water supply, about 321,000,000 mi3 (1,338,000,000 km3) is stored in oceans. That is about 96.5 percent of all Earth's water. It is also estimated that the oceans supply about 90 percent of the evaporated water that goes into the water cycle.
The water in the oceans is saline (saltwater). Saline water contains significant amounts (referred to as "concentrations") of dissolved salts. In this case, the concentration is the amount (by weight) of salt in water, as expressed in "parts per million" (ppm). Water is saline if it has a concentration of more than 1,000 ppm of dissolved salts; ocean water contains about 35,000 ppm of salt.
The volume of the oceans does change ... slowly
Of course, nothing involving the water cycle is permanent, even the amount of water in the oceans. Over the "short term" of hundreds of years, the oceans' volumes don't change much. But the amount of water in the oceans does change over the long term. During the last Ice Age, sea levels were lower, which allowed humans to cross over to North America from Asia at the (now underwater) Bering Strait.
During colder climatic periods, more ice caps and glaciers form, and enough of the global water supply accumulates as ice which lessens the amount in other parts of the water cycle. The reverse is true during warm periods. During the last ice age glaciers covered almost one-third of Earth's land mass, with the result being that the oceans were about 400 feet (122 meters) lower than today. During the last global "warm spell," about 125,000 years ago, the seas were about 18 feet (5.5. meters) higher than they are now. About three million years ago the oceans could have been up to 165 feet (50 meters) higher.
Oceans in movement: Tides
The oceans are always in movement. The moon influences daily tides, which make the beach a more interesting place to go. Tides vary greatly around the world, and in some places can be quite dramatic. The highest tides occur in confined estuaries, such as the Bay of Fundy, Nova Scotia, Canada, Ungava Bay, Quebec, and Bristol Channel in Britain. The Bay of Fundy has maximum tides of up to 53 feet (16 meters) during certain times of the year (Bay of Fundy Com).

Credit: NASA. Map by Robert Simmon
Oceans in movement: "Rivers" in the oceans
Did you know that the oceans move because of more than just waves driven by winds? There are currents and "rivers" in the oceans that move massive amounts of water around the world. These movements have a great deal of influence on the water cycle. The Kuroshio Current, off the shores of Japan, is the largest current. It can travel between 25 and 75 miles (40 and 121 kilometers) a day, 1-3 miles (1.4-4.8 kilometers) per hour, and extends some 3,300 feet (1,000 meters) deep.
The Gulf Stream is a well-known stream of warm water in the Atlantic Ocean, moving water from the Gulf of Mexico across the Atlantic Ocean towards Great Britain. At a speed of 60 miles (97 kilometers) per day, the Gulf stream moves 100 times as much water as all the rivers on Earth. Coming from warm climates, the Gulf Stream moves warmer water to the North Atlantic. Cornwall, at the southwest corner of Great Britain, is sometimes referred to as the "Cornish Riviera" because of the milder climate attributable to the Gulf Stream—palm trees (albeit a hardy variety) can even grow there, all because of the Gulf Stream.
The Gulf Stream carries warm, salty water northward along the Northeast Shelf (Gulf of Maine to Cape Hatteras, NC), bringing heat from the tropics to higher latitudes. The northward and landward extent of warm Gulf Stream waters affects ecological processes in the ocean, including the distribution of commercially important fish species. It also affects weather in the region. The Gulf Stream returns a considerable amount of heat to the atmosphere. See NASA’s data visualizations of the Gulf Stream.
How much water exists in the oceans?
Where is Earth's water?
For an estimated explanation of where Earth's water exists, look at this bar chart. You may know that the water cycle describes both the storage and the movement of Earth's water, so realize that the chart and table below represent the presence of Earth's water at a single point in time. If you check back in a thousand or million years, no doubt these numbers will be different as the distribution of water changes.
Notice how of the world's total water supply of about 332.5 million cubic miles of water, over 96 percent is saline. And, of the total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Fresh surface-water sources, such as rivers and lakes, only constitute about 22,300 cubic miles (93,100 cubic kilometers), which is about 1/150th of one percent of total water. Yet, rivers and lakes are the sources of most of the water people use everyday.
Water source | Water volume, in cubic miles | Water volume, in cubic kilometers | Percent of total water |
---|---|---|---|
Oceans, seas and bays | 321,000,000 | 1,338,000,000 | 96.5% |
Total global water | 332,500,000 | 1,386,000,000 | -- |
Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp. 817-823.
More topics and other components of the water cycle:
Precipitation and the Water Cycle
Streamflow and the Water Cycle
Snowmelt Runoff and the Water Cycle
Evaporation and the Water Cycle
The Atmosphere and the Water Cycle
Condensation and the Water Cycle
Infiltration and the Water Cycle
Sublimation and the Water Cycle
Surface Runoff and the Water Cycle
Ice, Snow, and Glaciers and the Water Cycle
Groundwater Flow and the Water Cycle
Groundwater Storage and the Water Cycle
Below are multimedia items associated with the water cycle.
- Overview
The oceans are, by far, the largest storehouse of water on earth — over 96% of all of Earth's water exists in the oceans. Not only do the oceans provide evaporated water to the water cycle, they also allow water to move all around the globe as ocean currents.
• Water Science School HOME • The Water Cycle •
Water cycle components » Atmosphere · Condensation · Evaporation · Evapotranspiration · Freshwater lakes and rivers · Groundwater flow · Groundwater storage · Ice and snow · Infiltration · Oceans · Precipitation · Snowmelt · Springs · Streamflow · Sublimation · Surface runoff
The oceans contain the majority of all water on Earth - almost 97% of global water is stored in oceans. The ocean is a huge storehouse of water
When we talk about the water cycle, we must consider both where water is stored in pools, and the fluctuation of water between those storehouses. Much more water is "in storage" for long periods of time than is actively moving through the cycle. It is estimated that of the 332,500,000 cubic miles (mi3) (1,386,000,000 cubic kilometers (km3)) of the world's water supply, about 321,000,000 mi3 (1,338,000,000 km3) is stored in oceans. That is about 96.5 percent of all Earth's water. It is also estimated that the oceans supply about 90 percent of the evaporated water that goes into the water cycle.
The water in the oceans is saline (saltwater). Saline water contains significant amounts (referred to as "concentrations") of dissolved salts. In this case, the concentration is the amount (by weight) of salt in water, as expressed in "parts per million" (ppm). Water is saline if it has a concentration of more than 1,000 ppm of dissolved salts; ocean water contains about 35,000 ppm of salt.
The volume of the oceans does change ... slowly
Of course, nothing involving the water cycle is permanent, even the amount of water in the oceans. Over the "short term" of hundreds of years, the oceans' volumes don't change much. But the amount of water in the oceans does change over the long term. During the last Ice Age, sea levels were lower, which allowed humans to cross over to North America from Asia at the (now underwater) Bering Strait.
During colder climatic periods, more ice caps and glaciers form, and enough of the global water supply accumulates as ice which lessens the amount in other parts of the water cycle. The reverse is true during warm periods. During the last ice age glaciers covered almost one-third of Earth's land mass, with the result being that the oceans were about 400 feet (122 meters) lower than today. During the last global "warm spell," about 125,000 years ago, the seas were about 18 feet (5.5. meters) higher than they are now. About three million years ago the oceans could have been up to 165 feet (50 meters) higher.
Oceans in movement: Tides
The oceans are always in movement. The moon influences daily tides, which make the beach a more interesting place to go. Tides vary greatly around the world, and in some places can be quite dramatic. The highest tides occur in confined estuaries, such as the Bay of Fundy, Nova Scotia, Canada, Ungava Bay, Quebec, and Bristol Channel in Britain. The Bay of Fundy has maximum tides of up to 53 feet (16 meters) during certain times of the year (Bay of Fundy Com).
Sources/Usage: Some content may have restrictions. Visit Media to see details.This map shows sea-surface temperatures of the North Atlantic Ocean. Data are from NASA satellite observations. Cold waters are shown in darker colors, whereas orange and yellow indicate the warmest temperatures. The Gulf Stream is visible as a warm water current traveling northward along the coast of North America and eastward into the central Atlantic Ocean. As it continues its journey heat from the ocean is lost to the atmosphere, warming the air above it. Cornwall and its palm trees are located southwest of London, and if you draw a line westward, you'll end up near Newfoundland, Canada. Cornwall and Newfoundland might be at similar latitudes, but you would be hard-pressed to find any palm trees growing in eastern Canada!
Credit: NASA. Map by Robert SimmonOceans in movement: "Rivers" in the oceans
Did you know that the oceans move because of more than just waves driven by winds? There are currents and "rivers" in the oceans that move massive amounts of water around the world. These movements have a great deal of influence on the water cycle. The Kuroshio Current, off the shores of Japan, is the largest current. It can travel between 25 and 75 miles (40 and 121 kilometers) a day, 1-3 miles (1.4-4.8 kilometers) per hour, and extends some 3,300 feet (1,000 meters) deep.
The Gulf Stream is a well-known stream of warm water in the Atlantic Ocean, moving water from the Gulf of Mexico across the Atlantic Ocean towards Great Britain. At a speed of 60 miles (97 kilometers) per day, the Gulf stream moves 100 times as much water as all the rivers on Earth. Coming from warm climates, the Gulf Stream moves warmer water to the North Atlantic. Cornwall, at the southwest corner of Great Britain, is sometimes referred to as the "Cornish Riviera" because of the milder climate attributable to the Gulf Stream—palm trees (albeit a hardy variety) can even grow there, all because of the Gulf Stream.
The Gulf Stream carries warm, salty water northward along the Northeast Shelf (Gulf of Maine to Cape Hatteras, NC), bringing heat from the tropics to higher latitudes. The northward and landward extent of warm Gulf Stream waters affects ecological processes in the ocean, including the distribution of commercially important fish species. It also affects weather in the region. The Gulf Stream returns a considerable amount of heat to the atmosphere. See NASA’s data visualizations of the Gulf Stream.
How much water exists in the oceans?
Where is Earth's water?
For an estimated explanation of where Earth's water exists, look at this bar chart. You may know that the water cycle describes both the storage and the movement of Earth's water, so realize that the chart and table below represent the presence of Earth's water at a single point in time. If you check back in a thousand or million years, no doubt these numbers will be different as the distribution of water changes.
Notice how of the world's total water supply of about 332.5 million cubic miles of water, over 96 percent is saline. And, of the total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Fresh surface-water sources, such as rivers and lakes, only constitute about 22,300 cubic miles (93,100 cubic kilometers), which is about 1/150th of one percent of total water. Yet, rivers and lakes are the sources of most of the water people use everyday.
One estimate of global water distribution Water source Water volume, in cubic miles Water volume, in cubic kilometers Percent of total water Oceans, seas and bays 321,000,000 1,338,000,000 96.5% Total global water 332,500,000 1,386,000,000 -- Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp. 817-823.
- Science
More topics and other components of the water cycle:
Filter Total Items: 15Precipitation and the Water Cycle
Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. Precipitation is the main way atmospheric water returns to the surface of the Earth. Most precipitation falls as rain.Streamflow and the Water Cycle
What is streamflow? How do streams get their water? To learn about streamflow and its role in the water cycle, continue reading.Snowmelt Runoff and the Water Cycle
Perhaps you've never seen snow. Or, perhaps you built a snowman this very afternoon and perhaps you saw your snowman begin to melt. Regardless of your experience with snow and associated snowmelt, runoff from snowmelt is an important component of the global movement of water, possibly even if you live where it never snows. Note: This section of the Water Science School discusses the Earth's...Evaporation and the Water Cycle
Evaporation is the process that changes liquid water to gaseous water (water vapor). Water moves from the Earth’s surface to the atmosphere via evaporation.The Atmosphere and the Water Cycle
The atmosphere is the superhighway in the sky that moves water everywhere over the Earth. Water at the Earth's surface evaporates into water vapor, then rises up into the sky to become part of a cloud which will float off with the winds, eventually releasing water back to Earth as precipitation.Condensation and the Water Cycle
Condensation is the process of gaseous water (water vapor) turning into liquid water. Have you ever seen water on the outside of a cold glass on a humid day? That’s condensation.Infiltration and the Water Cycle
You can't see it, but a large portion of the world's freshwater lies underground. It may all start as precipitation, but through infiltration and seepage, water soaks into the ground in vast amounts. Water in the ground keeps all plant life alive and serves peoples' needs, too.Sublimation and the Water Cycle
Solid, liquid, and gas - the three states of water. We see water freeze, transforming into a solid form such as ice, and we see water evaporate, turning into gas, but... have you ever seen ice transform directly to gas? This process is called sublimation and you can read all about it below.Surface Runoff and the Water Cycle
When water "runs off" the land surface, that’s runoff! Due to gravity, the water you wash your car with runs down the driveway as you work, and rain runs downhill. Runoff is an important component of the water cycle.Ice, Snow, and Glaciers and the Water Cycle
The water stored in ice and glaciers moves slowly through are part of the water cycle, even though the water in them moves very slowly. Did you know? Ice caps influence the weather, too. The color white reflects sunlight (heat) more than darker colors, and as ice is so white, sunlight is reflected back out to the sky, which helps to create weather patterns.Groundwater Flow and the Water Cycle
Yes, water below your feet is moving all the time, but not like rivers flowing below ground. It's more like water in a sponge. Gravity and pressure move water downward and sideways underground through spaces between rocks. Eventually it emerges back to the land surface, into rivers, and into the oceans to keep the water cycle going.Groundwater Storage and the Water Cycle
The ground stores huge amounts of water and it exists to some degree no matter where on Earth you are. Lucky for people, in many places the water exists in quantities and at depths that wells can be drilled into the water-bearing aquifers and withdrawn to server the many needs people have. - Multimedia
Below are multimedia items associated with the water cycle.