Sieniäsjen is the undersea Realm of Terapersü, home to the merfolk and many mysterious sea creatures. While this Realm spans all of the seas throughout the land, there is one large community where many merpeople call home. Other merpeople live in smaller groups or individually across the ocean.
The undersea world is what you would expect from life under water. There are no great palaces where the merpeople live, but some live in sunken ships or ruins from ancient structures swallowed by the sea. Most perpeople live within a network of undersea caves, which is also the home of the mermaid queen. As mentioned in the merpeople topic, many merfolk live solitary lives in the vast ocean as well, though, and there are countless habitats throughout the seas where a merperson might use as a residence. Like most undersea habitats, there are colorful coral reefs, shallower, rocky coastal areas, kelp forests, seagrass meadows, undersea caves, and mid-ocean ridges. While merfolk do visit open ocean areas, they do not live there, and merpeople do not swim into the dark depths of the sea where light cannot touch. While merfolk sight is better than humans and they can see to the very edges of where sunlight touches, they cannot see where there is no light and therefore do not travel there.