Underwater communications equipment; underwater to surface communications equipment; surface to underwater communications equipment; underwater voice communications equipment; underwater video communications equipment; underwater image communications equipment; underwater data communications equipment; underwater to surface voice communications equipment; surface to underwater voice communications equipment; human to human underwater communications equipment; diver to diver underwater communications equipment; diver to machine underwater communications equipment; machine to diver underwater communications equipment; human to machine underwater communications equipment; machine to human underwater communications equipment; machine to machine underwater communications equipment; communications equipment for submersibles; communications equipment for underwater vehicles; communications equipment for remotely operated underwater vehicles; communications equipment for autonomous underwater vehicles; communications equipment for unmanned underwater vehicles; saltwater communication systems; fresh water communication systems; saltwater communications equipment; fresh water communications equipment; nodes for underwater communications; radio frequency (RF) underwater communications equipment; underwater communications equipment, namely head mounted communications equipment; digital underwater communications equipment; radio frequency (RF) transceivers; radio frequency (RF) receivers; radio frequency (RF) transmitters; radio frequency (RF) communications equipment; wireless communications equipment; communications equipment