Along the way to our first stop, Armando pointed out the numerous caves and boltholes visible along the way. "The Rock", as Corregidor was known to the U.S. Army, ended the war as something closer to a "Swiss Cheese", as the Americans and invading Japanese dug holes to shelter from bombardment and invasion.
According to Armando, "we're still discovering new ones today. Some of them are easy to enter, while some require expert exploration. You shouldn't just jump into any hole on the island, or you might not come back."