Today, I went on the tunnel rats tour. We went to see some of the tunnels that the Japanese used during the US invasion of the island. We saw three different tunnels.
One of the tunnels was there strictly as a military tunnel. It was cleared out. There was a network of carved tunnels within, yielding more than one way to get out of every room.
The third tunnel was combined for military and civilian. There was nothing elaborate here. We all commented on this one that the tour advertisement should have included clear advice on wearing hiking boots. It was steep, rocky, and wet getting down to it. Once inside, it did not flatten out. It remained steep, rocky, and wet. The stalagmites and stalactites were beautiful. I got a picture of one that looks like an apple.
One of things that happened during the war was that the Japanese army told the civilians hiding in the tunnels about all of the atrocities that the United States would visit on them if they were captured. In one tunnel (not one we saw today), 850 Okinawans committed suicide rather than risk those atrocities.
We did not come across any unexploded ordnance. 5000 pounds of it are removed from the island monthly, to the point that we had a brief on the importance of not touching anything we could not identify.