Sömmering is the lava-flooded remains of a lunar impact crater on the eastern edge of the Mare Insularum.
It was named after German doctor Samuel Thomas von Sömmerring.
The eastern rim is much thicker in girth, and resembles a curved ridge.
The open southern end of this crater overlaps the lunar equator.
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Sömmering.