Mars is the fourth planet from the Sun. This terrestrial planet has a rarefied atmosphere, with surface characteristics resembling plains, deserts, polar caps of Earth, and the cratered surface of the Moon.
Liquid water cannot be on Mars due to low atmospheric pressure, which is less than 1 percent of the atmospheric pressure on our planet.
The two polar ice caps seem to be made mostly of water. If only the south polar ice cap melted water cover Marse’s surface to a depth of 11 meters (36 feet).
Moreover, in 2016 NASA found a large volume of underground ice in the Utopia Planitia area. The amount of discovered water is equivalent to the size of water in Lake Superior.
The map below created by Reddit user Crukey presents the surface of Mars if, like Earth, 71% of its surface area was covered with water.
And this is how Mars would look like with water and vegetation.