It would seem that Vis is a bit like a Swiss cheese. For hundreds of years, whoever has ruled the island has hidden things away here. They have dug so many tunnels that no one is quite sure where they all are. The islands geographical location away from the coast has made it irresistible to governments and armed forces to build the Vis tunnels and hide secret stuff here.
During the communist times, the island was divided into sectors. Each sector tunnel manager was from a different nationality. A serb ran one. A Croat ran one etc. And they never spoke about their activities before they died.
During the second world war, Vis was a secret air base for the UK and America. The Germans never found it because a local road was used as the runway. As you walk around town today, you will notice that the local scuba diving club actually has an aeroplane on its logo because the planes that did not quite make it back are now popular dive sites.
Perhaps the easiest Vis tunnels to visit are the submarine pens but that is far from the complete story. There are nuclear shelters, and and all sorts of things hidden away down there. We were actually warned not to explore them by ourselves because it is very easy to get lost and there could well be old ammunition and explosives down there.
We decided to let sleeping dogs lie and just enjoy the beauty of the place. But if you enjoy military history, you can book a tour and learn a lot more about the secret stories of the Vis tunnels.