Ice lake Found on the Red Planet

Mars Express, the European Space Agency probe, has taken a photo of an ice disk on Vastistas Borealis, a large plain in Mars' northern hemisphere. The 'ice lake' itself is sitting within a 35 km wide and 2 km deep crater. It is apparently present throughout the year because the Martian temperature and pressure do not easily allow phase changes. And the lake is almost certainly not CO2-based because the CO2-polar ice cap in the north had already disappeared when Mars Express photographed the ice lake. The ice lake sighting is important because it means that evidence for past or present life may one day be found there, and accessible water for humans is preserved in the lake should humans ever wish to survive on Mars.

http://news.bbc.co.uk/2/hi/science/nature/4727847.stm