Pretty cool. Has anyone mapped the back side of the moon? Are there a bunch of impact craters there also?
yes and yes.

Obverse and Reverse. There are far more impact craters on the back because the earth shields the near side. All the major craters on the far side have names.
There are craters but no “maria” (plural of “mare”) on the far side of the moon. The reason is that the crust is thinner on the earth-side than the far side, for whatever reason.
Has anyone mapped the back side of the moon? Yes
Are there a bunch of impact craters there also? No