It appears that a body of liquid water has been found buried beneath layers of ice and dust on Mars’ south pole.
The discovery was made by the European Space Agency (ESA) using radar data collected during their Mars Express mission. Though the mission has been in progress since 2003, this is their first major piece of evidence that liquid water currently exists anywhere on the red planet.
The discovery was made using MARSIS, the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument, housed within the Mars Express orbiter. It found an especially bright radar reflection in the south polar region of Mars.
Source: IGN.com Scientists Believe They Have Found Liquid Water on Mars