There is more to this well than meets the eye.

The castle walls are all made out of limestone and believe it or not they were all collected from the surrounding areas. All of the mountains surrounding the castle are actually made from this same stone. Whenever it rains, the castle walls and the mountains surrounding it soak up the water and it slowly makes it way through the rock. What do you think would happen if you were to break open the rock? Exactly. The water would start to drip out of the rocks just like a limestone cave where water drips from.

So how do you go about preserving the water that drips down from the castle? The bottom of these wells are lined with “Shimajiri mudstone” or “kucha” in Okinawan. Unlike the limestones, this mudstone is solid and water can’t move through it. Using this property, the mudstone preserves the falling water.

This is a mechanism of the Okinawan wells. If we are speaking in extremes, you should imagine that the whole island of Okinawa is made up of limestone and that all of the rain that falls in from the sky soaks into the island. Underneath this island of limestone however, lies a layer of mudstone that dams up the water as it soaks through the surface and it ends up pooling under. Meaning that if you were to start digging up the ground you would have to go through a layer of water before reaching the mudstone. Thanks to this, wherever you go in Okinawa, even in the highest mountain, you could make a well and settle around it as opposed to other societies which had to build themselves around large bodies of water.

By the way, if you look closely you will notice that there are holes built into the Ufuga Well. These are a mechanism that allows water to flow out and down from the sides when the water builds up too high. This makes it so the water can flow down to the people living below the cliffs as well instead of staying above ground.