There is nothing "beneath" the Moon, in the conventional "below" sense. The far side of the Moon, simply refers to the side of the Moon that faces away from Earth. However, if you mean to ask what the the composition and features are like on the far side of moon; it is dominated by vast expanses of ancient, heavily cratered highlands and a couple of large impact basins. Notable features on the far side of the Moon include prominent craters like the Apollo crater and the Mare Crisium, which is a large impact crater that is partly covered by younger volcanic plains. In general, the far side of the Moon's geology and appearance is quite different from the near side, which exhibits more pronounced dark and light areas known as maria and highlands.