Oceans and seas are vast bodies of saltwater that cover about 71% of the Earth's surface. The five major oceans are the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean, and Arctic Ocean. They play a crucial role in regulating the planet's climate and supporting diverse ecosystems. Seas are smaller than oceans and are often partially enclosed by land. Examples include the Mediterranean Sea and the Caribbean Sea. Both oceans and seas are vital for transportation, fishing, and recreation, providing resources and habitats for countless marine species.