Zach est un cratère de 71 Km et profond de 3700 m situé dans le secteur hautement cratérisé du limbe lunaire australe. Au nord on trouve le cratère, à piton central, Lilius (61 Km), au Nord-est Jacobi (68 Km) avec ses craterlets sur le plancher du cratère. Les murs intérieurs de Zach sont en terrasse. Les murs externes sont encadrés par des cratères qui forment un carré. Le fond est relativement plat avec quelques craterlets, dont un couple au centre et une double crête centrale excentrée au nord.

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Zach is a lunar impact crater located in the heavily-cratered southern sector of the moon. To the north is Lilius crater, while to the southeast is Pentland and to the south the larger Curtius crater. Due to foreshortening, the crater has an oblong appearance when viewed from Earth.
The inner walls of the crater are prominently terraced, while parts of the outer wall are indented by lesser craters. There are adjacent craters attached to the northeast, southwest, and southern parts of the rim. There is also a pair of overlapping craters on the northwest rim. The bottom is relatively flat with a few craterlets and a double central peak offset to the north.