How deep did they get? Hope she kept an eye on it, unsupported holes quickly get dangerous, people underestimate how much weight is in the soil if the sides give out and just how dangerous that amount of weight moving can be.

It was more sprawling than deep. It was a series of trenches connecting "rooms". I know they also had "water features" at some points, but the water would soak into the ground pretty quickly then be a mess for a few days, so they didn't do that.

No collapses happened and everyone is still alive. :-)