Ocean is a word that describes a massive body of salt water that covers more than 71% of the Earth’s surface. Depending on the context, the word ocean can be used to refer to a specific sea or to the world’s entire marine ecosystem. The terms ocean and sea are often used interchangeably, especially in casual speech. However, for people who work in the maritime field, there is a difference between the two words: The term ocean can be used to describe a particular sea or a vast body of water, while the term sea usually refers to a smaller portion of an ocean that is bounded by land in some way.
The ocean is vital for life on Earth: It supplies most of the planet’s oxygen and stores carbon, and it influences weather patterns by transferring heat from the equator to the poles and back again. It also influences global climate through the constant transfer of heat from the surface to the atmosphere and through evaporation, which brings rain to land surfaces.
Scientists are studying the ocean to understand how it works and what it contains. For example, a recent project at Woods Hole Oceanographic Institution (WHOI) aims to use uncrewed vehicles to explore the deepest part of our oceans. Film producer and director James Cameron recently made history by diving to the bottom of the Mariana Trench, a cavernous depth of 6,875 feet (2,091 meters), in a submersible that he helped design.
Whether scientists are studying the biodiversity of the ocean or the role it plays in global climate, oceans are very complex. Ocean waters can vary significantly in temperature, salinity, color, and other properties depending on where they are located on the planet. These differences are important because they can impact ocean life and human activities.
The color of ocean water is determined by the presence of living phytoplankton, which contain chlorophyll pigments. When satellites detect this color in long-term composite images, they can estimate the amount of photosynthesis taking place in the water.
In addition to phytoplankton, other major contributors to ocean color include dissolved organic matter and non-living particles like marine snow and mineral sediments. The color of the water is also affected by how much incoming sunlight is absorbed and how quickly the water moves as it flows past land.
In general, oceans are divided into five major bodies of water by researchers who study the ocean: The Pacific, Atlantic, Indian, Southern, and Arctic Oceans. These five oceans share a number of physical characteristics, but their geographic boundaries are arbitrarily defined by the continents that frame them.