Spiderholes are smaller than foxholes, and a little deeper. If you put three or four manhole covers over the top of it, you can ride out anything that doesn't directly hit you, turn your hole into an oven, collapse the hole or heavier than air chemical weapons. It's not diving for cover, it's retreating into a bunker. :P

Uh oh, I just remember something. I'm claustraphobic!