A submersible raft device that is primarily used for aquaculture farming. The raft device has a raft surface, a buoyance support structure, and a submersion control system. The buoyance support structure and the submersion control system allow the raft to be submerged to a desired depth beneath the ocean surface. When used for certain kinds of aquaculture farming, such as mussel farming, submerging the raft below the surface protects the raft, as well as the mussels growing on ropes suspended from the raft, from damage in times of hazardous sea conditions.