Greatest water coverage (planet)

With approximately 71% of its surface covered in liquid water, Earth truly earns its reputation as the "Blue Planet". That coverage total increases to 81% if frozen water (i.e., ice sheets and glaciers) are also factored in.

In terms of volume, Earth has an estimated 1,361,620,510‬ km³ (326,666,904 cubic miles) of water in or around it in the atmosphere.

Earth's oceans and seas hold 1,338,000,000 km³ (321,000,000 cubic miles), accounting for 98.2% of all the liquid water on Earth. When combined with the contents of saline aquifers and lakes, the proportion of the planet's liquid water that is saline climbs to 99.2%. Liquid freshwater accounts for only 0.8 percent of all the water on Earth as most of the freshwater (68% of it) is frozen in permafrost, glaciers and ice caps.

Although there are no other planets in the Solar System with liquid water on the surface, there are a few ice worlds where it is thought that an ocean of liquid water exists beneath an icy crust many kilometres thick. The most comprehensively studied of these ice worlds is Saturn's 500-km-wide (310-mile) moon Enceladus, which has a subsurface ocean that makes its presence known through a series of geysers around the south pole. Models based on the gravitational field of the moon suggest that Enceladus' ocean may have a volume of roughly 15,000,000 km³.

NASA planetary scientist Steve Vance has estimated that Ganymede, the largest moon of Jupiter (and the entire Solar System), may hold as much as 35.4 zettalitres (one zettalitre is 10^18 m³) of liquid water. This would mean 69% of the moon's total volume is liquid water, although at this stage this is only theorized.