The Undersea is a pocket ocean underneath Xebel's seafloor,[1] containing the ruins of ancient Atlantis's capital. It is riddled with erupting thermal vents, and gigantic sea monsters.[2]
The Undersea first came to the attention of King Orin after he had The Watchtower perform a deep geoscan of the area around Xebel. The scans showed the thinnest point of Xebel's seafloor covering it was at the Grave of Legends. He ordered Aquaman to take a covert team there in search of Arion's crown.[1]
The Undersea June 02, 15:23UTC-2
Aquaman, Wyynde, La'gaan and Delphis drilled through the seafloor at the Grave of Legends and entered the Undersea. They found the body of a statue whose head sat in the Grave of Legends. Their tunnel collapsed behind them, causing a wider cave in, forcing them to rush further into the undersea, drilling through another barrier.[1]
After the group dodged yet another thermal vent, they encountered a crab monster. After convincing the crab they were not edible, the found a fissure where it emerged, leading them down to an older section where the ruins of the Atlantean capital lay. Arion's skeleton lay half crushed beneath the head of a statue of Varl'jat. After finding Arion's crown, they were attacked by Leviathan, but rode the massive creature up to the top of the Undersea, and used it to ram a hole in the ceiling, allowing them to escape the pocket ocean.[2]