The Central Hall is a massive, columnar room in the center of Marige Atoll (Known as Mo'ia Atoll in the American Release) that is particularly notable for its resident large pod of Bottlenose Dolphins. At night, a rather sizable group of Nomura's Jellyfish can be seen floating about above the Hall. Several shoals of small fish make their homes in the Hall, including a quick-moving shoal of Chub Mackerel.
At the very bottom of the room, a medium-sized tunnel leads to one of the six inscriptions found all around the ruins. Another hallway off to the side would lead you inside the ruins if it weren't for an ancient mechanism spouting water at a high pressure at the other end of the hallway, and so creating a current that sweeps you backwards if you swim into it (rather, if you attempt to swim into it).
On the floor of this room, a single piece of the Inscribed Nephrite treasure can be found, under a zoom-mode spot, roughly in the centre of the area.