Craterland

MESSENGER's Narrow Angle Camera (NAC) on the Mercury Dual Imaging System (MDIS) acquired this view of Mercury’s surface illuminated obliquely from the right by the Sun. The unnamed crater (about 52 Km in diameter) in the center of the image displays a telephone-shaped collapse feature on its floor.
Such a collapse feature, not seen on the floors of other craters in this image, could reflect past volcanic activity at and just below the surface of this particular crater.

The crater is located in the Southern Hemisphere of Mercury, on the side that was not viewed by Mariner 10 during any of its three flybys (1974-1975).
This scene was imaged while MESSENGER was departing from Mercury from a distance of 19.300 Km (approx. 12.000 miles), about 1 hour after the spacecraft's closest encounter with Mercury.
The image is of a region approx. 236 Km (about 147 miles) across, and craters as small as 1,6 Km (1 mile) can be seen.