The IM-A-761 oceanic garrison, alternatively referred to as The Blackfathom, represented a more recent type of Imperial garrison. These garrisons were specifically designed by Rothana Heavy Engineering for planets characterized by expansive oceans.
Due to its aquatic nature, a Blackfathom garrison did not possess underground levels. However, this was offset by the inclusion of numerous robust repulsorlifts which ensured its buoyancy, even in the face of significant wave action. Furthermore, it featured specialized underwater hangar bays. The forces stationed there comprised seatroopers, repulsor-subs, and AT-AT swimmers. It's suggested that the repulsorlifts' capacity to endure severe wave conditions stemmed from an occurrence on Shaum Hii that triggered a NewsNet media uproar.