Valles Marineris on Mars is a chasm 125 miles wide, more than 6 miles deep and stretching for almost 2,500 miles, making it the largest canyon in the solar system.
It is 10 times longer and five times deeper than Earth's Grand Canyon, a release from the Paris headquarters of the European Space Agency said Monday.
The latest image of Valles Marineris, in near-true color, was created from data captured during 20 individual orbits of ESA's Mars Express.
The canyon's formation is likely linked with the formation of the largest volcano in the Solar System, Olympus Mons, scientists said.
Volcanic activity is indicated by the nature of the rocks in the walls of the canyon and the surrounding plains, which were built by successive lava flows, they said.
Strong water flows may have reshaped the chasm after it was formed, since mineralogical evidence collected by orbiting spacecraft, including Mars Express, suggests the terrain was altered by water hundreds of millions of years ago.