To quote wikipedia:

In crystallography, the space group of a crystal splits as the semidirect product of the point group and the translation group if and only if the space group is symmorphic

The if and only if is interesting: The geometry ofthe crystal lattice truly appears to capture the structure of the semidirect product. It's a discrete object as well, which makes it way easier to visualize. I'm going to hunt down the definitions involved so I can finally feel like I truly understand semidirect products from the "action" perspective.