The ocean, which covers 70 percent of Earth’s surface, is the principal component of our planet’s hydrosphere. It makes life possible on Earth and makes the planet appear blue from space. The ocean’s chemistry, temperature, salinity and density vary greatly with latitude and time of year. This variation is called the global oceanic cycle, and it regulates many of the planet’s processes.
As a result, the ocean is known for its incredible biodiversity. Its inhabitants range from microscopic organisms, such as phytoplankton, to giant cetaceans, such as the blue whale – the largest creature on the planet, which can reach 33 meters (108 feet) in length. Marine life also plays a vital role in the food chain and is essential to the health of land and sea animals.
When humans first explored the ocean, they learned about its immense power and beauty. They used it as a source of transport, commerce and exploration. Today, we still rely on it for food and its natural resources.
Water is everywhere on Earth, but the vast majority of it – some 97 percent – is in the ocean. The ocean’s incredibly abundant life makes it the most diverse habitat on the planet. Its awe-inspiring size, depth and color have fascinated people for centuries.
The Earth’s ocean is made up of five distinct regions: the Pacific, Atlantic, Indian, Arctic and Southern Oceans. These separate, but merge into a single, massive body of water that oceanographers call the global ocean.
Although the ocean is one continuous system, scientists have drawn distinct boundaries between its various zones based on their characteristics. These zones include thermoclines (temperature), haloclines (salinity), chemoclines (chemistry) and pycnoclines (density).
The ocean is powered by a complex, non-linear, global circulation system that is driven by the Coriolis effect, planetary rotation, thermal expansion, differences in temperature and salinity, as well as wind and waves. The Gulf Stream, for example, is a powerful current that flows north along the United States’ eastern coastline. It carries warm surface waters from the Caribbean Sea and transports colder, dense deep currents in its wake.
When the molten rocks that formed the Earth cooled, they released water vapor that covered its crust with a primitive ocean. This water absorbed heat from the sun and slowed down the Earth’s rotation, creating the Coriolis effect. It causes large systems like winds and ocean currents to veer clockwise in the Southern hemisphere and counterclockwise in the Northern hemisphere.
The ocean’s movement also drives upwelling, a process that brings surface waters to the surface. In some places, this upwelling brings nutrients that feed new growth of plankton. This constant cycling of energy and food throughout the ocean allows it to sustain life. In turn, the healthy ocean provides us with a variety of benefits from improved cardiovascular health to a rich supply of minerals. The key is to get out and enjoy it! Swimming in the ocean is a fantastic cardio workout, but the best part is that it stimulates circulation of oxygen-rich blood throughout your entire body.