Salt water: oceans and seas
Look at a photo of the Earth from space: it is mostly blue! About 70% of the surface of the Earth is covered in water. All this water is part of the hydrosphere. We find water in oceans and seas, but also in rivers, lakes, glaciers and under the ground, in aquifers.
Oceans and seas
Almost all the water on Earth (more than 95%) is in the oceans and seas. It is salt water, so we cannot drink it.
Enormous areas of salt water between the continents. They are all connected. There are five: the Pacific (the biggest), the Atlantic, the Indian, the Southern and the Arctic (the smallest).
Smaller than oceans and partly surrounded by land. Seas are part of an ocean. Example: the Mediterranean Sea.
Spain has water on three sides! The Cantabrian Sea is in the north, the Atlantic Ocean is in the west and south-west, and the Mediterranean Sea is in the east and south. The Canary Islands are in the Atlantic Ocean, and the Balearic Islands are in the Mediterranean Sea.
Both have salt water. An ocean is enormous and open, between continents. A sea is smaller and it is partly surrounded by land.