Island Tunnels

The surface expedition sent down to … started to investigate one of the round islands, and soon made a remarkable discovery. The island had a complex tunnel network running beneath it, winding through the strange, oily rock. These tunnels were remarkably even and round, and laced the entire island. They seem to be natural formations, not intentionally excavated, but they have certainly not been shaped in a conventional, geological manner.

The command below will trigger the "Island Tunnels" event in Stellaris:

When this event fires, you can choose between the following option:

• Keep digging!