Melas Chasma, a huge canyon forming part of the 4000-kilometer Valles Marineris rift valley on Mars, plunges 9 kilometers below the surrounding plains in this image, which was taken by the High Resolution Stereo Camera on the European Space Agency's Mars Express orbiter, making it one of the deepest depressions on Mars.
The image also shows evidence that water once flowed and lakes once stood on the Martian surface. White lines are channels cut by water and lighter-coloured regions indicate deposits of sulphate components. Rock formations display evidence of flow textures, indicating that they were once deposited by liquid water, water ice or mud.
Image credit: ESA/DLR/FU Berlin (G. Neukum)/Released by the German Aerospace Center