MerpolisMerpolis is the underwater city within the inland sea called the Rear Gulf. It is carved from the mountains of white stone and richly decorated by mermaids, the descendants of the ancient civilization of artists and sculptors. It probably has more decorations than the rest of the world put together: it's literally filled with sculptures made of white stone, which is the main material for sculpting under the sea.
But Merpolis does also have a deeper level, with even more miraculous creatures who don't feel comfortable in the shallow waters. The bodies of the deep ones are very soft, able to comform to the great underwater pressure, and their limbs often reach the state of tentacles in their softness and shapes. They have jelly-like skin and sluggish features.