A SHIELD facility located in the Atlantic Ocean off the East coast of Florida. It is used for oceanic research, and serves as a convenient place to have meetings with diplomats and couriers from Atlantis.
It is staffed by a contingent of some 50 or so SHIELD agents and researchers, as well as a small permanent delegation of Atlantean scientists how assist in the research. The SHIELD Super-Agent code-named Stingray is the main security force for the facility.
Hydro-Base was recently attacked by the forces of Hydra during its coordinated assault on SHIELD. It was damaged badly enough to sink it, and several members of its staff (including Stingray) are missing and presumed kidnapped by Hydra. (Assembly Required #2)