How would our neighbour Mars look if there was liquid water on its surface? Here is a nice image of how you could see it from about 6000 km above its surface. The big round island on the upper left would consist of Albor Tholus and Elysium Mons, two extinct volcanoes standing 4.5 km and 13.9 km above their surrounding lava plains. This image has been produced by using the real topographic map of Mars. If you want to understand why the planet doesn't look like this anymore (but has looked similar to this image in the past) read our article about Mars.