A large expanse of water is commonly referred to as either a sea or an ocean, and while these terms are often used interchangeably, there is an important distinction between them based on their size and geographical characteristics.
What's the difference between an ocean and a sea?
Oceans are the Earth's largest bodies of water, covering approximately 70 percent of the planet's surface. Seas, on the other hand, are smaller bodies of water typically located where the ocean meets land. They are found at the edges of the ocean, where portions of the ocean are partially enclosed by land.
- How deep is the deepest part of the ocean?
- Why don’t deep-sea animals implode? Here's how they survive extreme pressures at the bottom of the ocean
Ocean currents have a significant impact on climate, geography, and environmental conditions. For instance, the Atlantic Gulf Stream, driven by the North Atlantic Ocean current, transports warm air from the Gulf of Mexico to Europe.
Although we typically refer to the five distinct oceans – Pacific, Atlantic, Indian, Southern, and Arctic – they actually form one vast interconnected body of water, while seas are separated by land.
A sea is a part of an ocean where it meets land. For example, the North Sea is considered a sea because it's situated between two land masses – the British Isles and the European continent – and is connected to both the Atlantic and Arctic oceans.
Seas are also much shallower than oceans, and there are around 50 seas around the world, compared to the fewer, much larger oceans.
Are there any exceptions to this rule?
Yes! The Sargasso Sea is considered a sea despite not having a land border. This is because it is enclosed by four ocean currents that create a gyre (vortex) around it.
Then there are inland seas, which are surrounded by land or connected to an ocean through a river, strait, or an 'arm of the sea.' Examples of inland seas include the Black Sea, the Sea of Marmara, and the Baltic Sea.