Enormous water-filled warship of the Xindi-Aquatics, the cautious council members whose decision to side with Archer turned the battle over the Xindi weapon.
Xindi-Aquatic cruisers were the largest ships of the Xindi, flooded vessels built for the aquatic members of the Xindi Council. The Aquatics were slow and deliberate, and on the Council they were long undecided between the Reptilians and Insectoids on one side and the Primates and Arboreals on the other.
In Countdown, Archer's promise to shut down the spheres of the Delphic Expanse, and the Reptilians' kidnapping of Hoshi Sato, persuaded the Aquatics that the Sphere-Builders were the true enemy. Their massive ships then joined Archer's Xindi allies against the Reptilian and Insectoid fleets defending the weapon.