The Montpellier Marine University had conducted expeditions to the Kermadec Trench, an underwater canyon, where at its 9000 meters deep a new species of fish was found. The fish's body was adapted to take on the great amount of the pressure caused by the depths at which it lived. After examination of specimen, the scholars found that those traits that allowed the fishes to survive deep underwater were not caused by evolution, but were caused by a virus. Such ability of adapting into a host caused the scholars at the university to call it simply "The Abyss".
After their discovery, the scholars decided to make another expedition to gather a greater amount of fish in order to gain larger quantities of the virus, since the virus itself could be lead to the development of B.O.W.s as the virus let its host to gain resistance to high pressure environments, the need of less oxygen to survive and increased heat resistance. Ultimately it was merged with the T-Virus to form the T-Abyss Virus.
↑Although the name suggests that it was found in the Abyssopelagic zone, anything deeper than 6 kilometres (20,000 ft) is part of the Hadopelagic zone.