The passages between the cave exits are hand-dug by either a team of kindred or some sort of huge underground predator.

Gas-powered railway carts are typically used to travel between cave entrances at high rates of speed.

All these connecting passages are tight one-way affairs. If two beings meet one another along the way, they must find a natural break in the passage for one to step off so another may pass. Unfortunately, these pass-ways are few and far between.

There are a variety of other entrances and exits from this system that are not common knowledge, and might be havens to other kindred.