The document discusses the hydrosphere and the global water cycle. It notes that the hydrosphere includes all water on, under, and over the surface of a planet. On Earth, the hydrosphere contains around 1,386 million cubic kilometers of water, with 97.5% being saline ocean water. It also describes the water cycle as the transfer of water between reservoirs like the atmosphere, oceans, lakes, ice caps, and soil. Around 70% of the Earth's surface is covered by water, with the oceans alone containing 96.5% of all water on the planet.