Lemuria

Lemuria had been a small continent and group of islands in the Pacific Ocean 21,000 years ago, which was ruled by the Deviants—the center of their empire. When the Deviants attacked Atlantis, the Atlantean King Kamuu opened the magma-pits which were the city's means of heating. This caused a chain reaction which collapsed and sank the continent. At that same time, when the Second Host of the Celestials came to Earth, the Deviants attacked them. In retaliation, the Celestials sank Lemuria in what is now known as the "Great Cataclysm." The Eternal Ikaris guided a ship of humans to safety. As the continent of Lemuria sank, some of the Deviants managed to survive by escaping to underground cities that had been previously constructed on the southern half of the continent. They built a new underground capital city-state called “The City of Toads,” (or Lemuria-East) from which the sea was shut out. The city was flooded much later by one of the Celestials, but most of its population survived and rebuilt the city.