The hydrosphere is defined as the total mass of found on, beneath, and above the surface of a planet, minor planet, or natural satellite.

Despite the fact that the ’s hydrosphere has been existing for roughly 4 billion years, it is still changing shape.

This is created by seafloor spreading and continental drift, which causes the land and to reorganize.

It is believed that the contains 1.36 billion cubic kilometers (332 million cubic miles) of .

This encompasses both liquid and frozen in groundwater, seas, lakes, and streams.

Fresh contributes for only 2.5 percent of this total, whereas saltwater accounts for 97.5 percent. 68.9 percent of this fresh is in the form of ice and permanent snow cover in the Arctic, Antarctic, and mountain glaciers; 30.8 percent is in the form of fresh groundwater; and just 0.3 percent is in conveniently accessible lakes, reservoirs, and systems.

The overall mass of the ’s hydrosphere is approximately 1.4 1018 tonnes, or approximately 0.023 percent of the total mass of the .

At any one time, around 20 1012 tonnes of this is present in the form of vapor in the ’s atmosphere (for practical purposes, 1 cubic meter of weighs one ton).

The covers around 71 percent of the ’s surface, an area of approximately 361 million square kilometers (139.5 million square miles).

The average salinity of the world’s oceans is around 35 grams of salt per kilogram of (3.5 percent ).