Have you ever heard of something called a box? When people build bridge piers, they first place a circle-shaped object welded with steel plates flat in the water, above the water surface, and continue to weld it until it sinks to the bottom of the water. isolates water from inside the steel ring. Open and drain the water in the steel ring, and workers can dig the soil into the steel ring. As they dig, the steel ring continues to sink and people continue to weld the steel ring. steel ring above the steel ring to form a water-insulating space, people build bridge piers in this space and they are not affected by water.
It is "Light Messenger", the protagonists are Dadi, Gas and Rabbi. The earth is like drawing circles on the ground, and time can bring messengers; Gas is like drawing circles in the wind; Rabbi is like drawing circles in the water, and he is the one you said standing on the disk after his transformation, he is the messenger of the waves. You can check on Baidu if this is the one you saw.