Mare Imbrium

Mare Imbrium (Latin for "Sea of Showers" or "Sea of Rains"), is a vast lunar mare filling a basin on Earth's Moon. One of the larger craters in the Solar System, Mare Imbrium was created when lava flooded the giant crater formed when a very large object hit the Moon long ago. The Moon's maria (plural of mare) have fewer features than other areas of the Moon because molten lava pooled in the craters and formed a relatively smooth surface. Mare Imbrium is not as flat as it was originally because later events have altered its surface.