These islands are all volcanic or coral. It is pretty hard stuff. When they excavate for a new project, they never build any retaining walls. The structure of the ground is enough. Currently, they are digging out a big hill of land. Here it is more than a hill. The part that is so interesting to us is that the earth strata are so evident. And - the shifting of the earth's crust when there have been earthquakes. See what we mean!