This is Palus Somni or the Marsh of Sleep.
It lies between Mare Crisium on the right and Mare Tranquillitatis on the left
and is the rough area to the left of the central bright crater. That
crater is Proclus and the larger one south of it is Macrobius.
The craters are much more evident when the terminator is
nearer but the marsh contrasts better with the seas when the light is more
Telescope: Meade LX200 GPS 10" SCT, f/10
Camera: Meade LPI
Capture Software: Autostar Suite
Settings: Auto Lunar
Exposure Count: 10 frames
Method: Auto stack and align