Ocean vs. Sea: What's the Difference?
Read the comparison below, or explore it visually. Create a visual lesson comparing ocean and sea using available credits or plan allowance.
An ocean is one of the five vast, open bodies of salt water that cover about 71% of Earth's surface, while a sea is a smaller body of salt water, usually partly enclosed by land and lying at an ocean's edge. The Arabian Sea, for example, is part of the Indian Ocean. Seas are generally shallower than the open ocean, though not always.
At a glance
| Ocean | Sea | |
|---|---|---|
| Size | Vast; the Pacific alone covers a third of Earth | Much smaller, a part of an ocean |
| Number | Five: Pacific, Atlantic, Indian, Southern, Arctic | Dozens, e.g. Arabian, Red, Mediterranean |
| Boundaries | Mostly bounded by continents | Usually partly enclosed by land or islands |
| Depth | Average about 3.7 km; deepest nearly 11 km | Often shallower, many over continental shelf |
| Floor | Mostly dense oceanic crust | Often continental crust near the coast |
Which should you use?
Use "ocean" for the major world water bodies between continents, such as the Indian Ocean that links India's coast with East Africa, Southeast Asia and Australia.
Use "sea" for a smaller, partly enclosed region of an ocean, such as the Arabian Sea off Mumbai or the Mediterranean Sea between Europe and Africa.