Mydians can navigate in the dark using their antennae and sense of smell, but you personally prefer to know what's coming from a long way off. You locate a flashlight and take a look. It looks extensive, and as far as you can smell, if there's an exit aboveground it's at least half a kilometer away.
There have already been a few notable cases of unexpected serendipity around this game today, which makes you think this secret tunnel in your cellar might be more helpful than logic would dictate. At the very least it could be a way to exit your house far from the fire. But if you're going to be gone for a while, you need to prepare.