* Impact Basin: The Sea of Tranquility is a large impact basin, meaning it was formed by a massive asteroid or comet colliding with the Moon.
* Filled with Lava: Over time, after the impact, volcanic activity filled the basin with lava, creating a flat, smooth surface. This lava flow smoothed out the original crater-like shape.
* Maria: The Sea of Tranquility is part of a group of dark, flat plains on the Moon called "maria" (Latin for "seas").
So, while it was formed by an impact, the subsequent lava flow transformed the original crater into a vast, smooth plain that we now call the Sea of Tranquility.
