This planet is perhaps 90% water, so there are no cities on the surface. But there is a vast underwater city that occupies about 40% of the ocean floor. When you look at the city, it looks like the coral reef grew to massive proportions because they used the reef as a design concept to make it look like there was nothing. There is no need for oxygen bubbles because the population of this world can breathe underwater. The ocean is teeming with abundant life, from fish to sea snails. The city uses the ocean floor to grow the plants it feeds on, namely kelp, seaweed, and many other things that I can't name. People use magic to move, using magic to repel water from their feet. This allows them to move effortlessly through the water. They get their energy from the ocean through a hydrofusion reactor, which gives them all the energy they need. People can stay above the water level for as long as they want, but the longer they stay out, the less magic they can use. Their ships use an improved hydrofusion reactor. They are designed to look like a manta ray. As you examine their civilization, you will realize that they have no government to govern them. Whenever an important decision needs to be made, they simply send one person from each city. They do it this way so that one person is not overwhelmed by power. This helps maintain peace and preserve their way of life.