[2031: Somewhere in the Luzon Strait] Under the cloak of night, an elite team of Navy SEALs makes its way to an uninhabited island, while fifty kilometers out at sea, a flotilla of autonomous underwater and surface vehicles (AUSVs) silently monitors enemy fleet movements. This isn’t a scene from a futuristic novel; it’s a glimpse into the near future of maritime defense, where the lines between warfare domains are blurring, and innovative hybrids are redefining mission sets.
The emergence of unmanned air systems (UAS) with amphibious and submersible capabilities is a potentially transformative development in maritime defense. Among the most mature of these cross-domain systems is the Naviator, developed at Rutgers University and now marketed by SubUAS LLC. “The Naviator is a quadcopter drone that can transition from the air to water depths of up to 1000 feet,” says John F. Williams, a U.S. Navy photographer who captured the drone in action. Its four rotors provide lift and maneuvering in the air and function as propellers underwater, enabling missions ranging from bridge inspection to harbor access reconnaissance, and showing potential for mine hunting, hull inspection, and search and rescue.
Another contender in this space is the F4, developed by Vancouver-based Seahawk Robotics. With its ruggedized, waterproof airframe, the F4 is designed to land, float, and operate on open water for extended periods. “For navies and commercial operators alike, the F4 can provide a rapidly deployable, targeted sensing or communication capability at dramatically reduced cost and logistical overhead,” says the company’s website.
The commercial sector is also contributing to this evolution. Chinese manufacturer SwellPro has carved out a niche with its SplashDrone 4, a self-righting, ruggedized, fully waterproof quadcopter that can fly, land, float on water, and take off again. And then there’s the HOVERAir Aqua, a pocket-sized, IP67-rated drone by Zero Zero Robotics. “The Aqua can float, stabilize, and even film below the ocean surface in ‘Snorkel Mode’ using its tilting 4K camera,” says the company’s website. While neither vehicle dives fully beneath the waves, they demonstrate how quickly amphibious UAS are maturing in the commercial space.
Imagine an autonomous vehicle that can operate both above and below the ocean surface, combining the persistence and communication advantages of a USV with the stealth capabilities of a UUV. Now imagine it is powered exclusively by wind and solar energy, and can be organized into distributed, high-endurance, attritable fleets for full-spectrum maritime surveillance. San Diego-based SubSeaSail has spent nearly a decade perfecting just such a vehicle. “HORUS is a compact, lightweight, monohull AUSV designed for persistent maritime operations and data collection,” says the company’s website. A patented, transparent wingsail enables low-signature operations at sea for months without fuel or maintenance, while its ability to submerge to depths of 100 meters allows it to evade detection or adverse weather conditions.
SubSeaSail’s HERMES, meanwhile, is a scalable, self-righting, semi-submersible trimaran designed for long-duration surface and subsurface operations, and is envisioned as a cargo and expeditionary power supply platform. “Like HORUS, HERMES can submerge to 100 meters to evade detection or ride out severe weather,” says the company’s website. With speeds of 5 to 15 knots, and large-volume payload space, it offers a high-speed, attritable platform for contested logistics.
Gulfport-based Ocean Aero has also developed a first-of-its-kind hybrid autonomous platform, the Triton. “Measuring approximately 4.5 meters in length and weighing 350 kilograms, its folding rigid sail, integrated solar panels, and electric drive enable months-long surface operations or dives to 200 meters for up to five days,” says the company’s website. In addition to surface surveillance, the Triton’s body payload capacity of 23 kilograms (with additional space in the wing and keel) enables underwater survey and intelligence operations, making it well suited for missions such as anti-submarine warfare (ASW), mine countermeasures (MCM), and critical infrastructure protection.
On the higher displacement end of the spectrum, the Leidos Sea Specter is an autonomous low-profile vessel (ALPV) developed for the U.S. Marine Corps to support distributed operations and contested logistics. “Inspired by semi-submersible ‘narco-boats,’ the 65-foot diesel-powered craft rides low in the water to minimize visual, radar, and infrared signatures,” says the