Jack Stewart just published his debut entry in the Ryanverse, Pressure Depth and it has a whole lot more to offer than you might think. It’s time for a deep dive (pun intended) into the murky, dangerous waters of the Pacific Ocean to unpack the centerpiece of Pressure Depth.
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In the novel, Jack Ryan Jr. and his team find themselves racing against a ruthless adversary to secure a terrifying piece of Cold War technology hidden on the ocean floor. But the true star of the opening act is not a human operator. It’s a drone. Specifically, it’s the extra-large uncrewed underwater vehicle known as the DARPA Manta Ray.
The blurring of reality and fiction is a hallmark of the Ryanverse and something Jack Stewart seems to be keen to get back to. But just how close to reality is the Manta Ray? As it turns out, the technology in Pressure Depth is not science fiction. It’s already here, and it’s poised to completely rewrite the rules of naval warfare.
The Real-World Leviathan: DARPA’s Manta Ray
Initiated in 2020 by the Defense Advanced Research Projects Agency, the Manta Ray program was designed to shatter the traditional limitations of unmanned underwater vehicles. For decades, submersibles were constrained by finite battery life and the need for constant maintenance by surface ships. The Manta Ray was conceived to achieve extreme endurance and operational independence, entirely negating the need for human logistical support.
Northrop Grumman, one of the primary defense contractors on the project, designed a full-scale extra-large demonstration system that completed comprehensive at-sea testing off the coast of Southern California in early 2024. The vehicle is a mechanical beast.
- The physical architecture abandons traditional cylindrical torpedo shapes in favor of a biomimetic glider design inspired by the giant oceanic manta ray.
- It features a massive lifting body with a 14-meter wingspan, a length of 10 meters, and a maximum displacement weight of up to 30 tons.
- Rather than relying on constant propeller thrust, it uses variable-buoyancy propulsion, pumping seawater into internal tanks to sink or rise and converting that vertical motion into forward glide.
Perhaps the most impressive real-world feature is its infinite endurance capability. By collaborating with a clean-energy startup named Seatrec, Northrop Grumman integrated a system that harnesses the ocean’s thermal gradients. As the glider dives into freezing abyssal depths and ascends to warmer surface waters, specialized phase change materials melt and expand, driving a hydraulic motor to generate electricity. This means the Manta Ray can theoretically recharge itself indefinitely.
If that’s not enough to keep adversaries awake at night, the massive 30-ton vehicle can be disassembled into subsections, packed precisely into five standard shipping containers, and rapidly assembled dockside anywhere in the world.
Fiction Meets Reality in Pressure Depth
In the pages of Pressure Depth, this exact technology serves as the inciting incident for a global crisis. The book opens with the Manta Ray undergoing trials off the coast of Guam near the Santa Rosa Reef, tethered to the operations of the USNS Salvor.
The novel brilliantly highlights the tactical applications of the drone:
- The fictionalized Manta Ray is testing a cutting-edge payload called the adaptive modular sonar array.
- This array utilizes Nereus, an autonomous threat detection artificial intelligence designed to filter out marine life and cross-reference sonar returns with known adversarial hardware.
- During a routine sweep, Nereus flags a massive anomaly 98 fathoms below the surface.
The AI identifies a 260-foot-long pressurized hull buried in the silt, which Chief Carla Bennett later confirms to be a Soviet installation marked with a hammer and sickle and the word Sirena. We eventually learn that Sirena is a massive threat.
The Global Undersea Arms Race
The technology featured in Pressure Depth points to a rapidly accelerating shift in modern combat. The strategic value of the ocean depths is increasing, and peer competitors are investing heavily in parallel capabilities.
While DARPA focuses on massive rigid-hull gliders, the People’s Republic of China is aggressively developing soft-bodied biomimetic robots. Researchers at Northwestern Polytechnical University in Xi’an have built submersibles utilizing flexible pectoral fins and fluidic actuators to mimic the exact undulating locomotion of biological rays. These drones generate practically zero hydrodynamic wake and can link together to form underwater acoustic swarms.
Meanwhile, the Russian Federation has developed the Status-6 Poseidon, a nuclear-powered autonomous torpedo designed for trans-oceanic strikes against coastal infrastructure. The ocean floor is rapidly becoming a heavily contested battlespace, and autonomous drones like the Manta Ray will be the primary sentinels patrolling it.
M.P. Woodward also covered this development in naval strategy in Red Tide, basically advocating for the “fifth platform”. And I covered this in my article “Red Tide” Rising: Are Aircraft Carriers Obsolete in a New Era of Naval Warfare?
The Future of the Ryanverse
What does this mean for John Clark, Jack Ryan Jr., and the rest of The Campus?
The introduction of platforms like the Manta Ray changes the operational environment entirely. The Campus is used to slipping through the cracks and operating in the shadows. But how do you stay hidden when the ocean floor is littered with autonomous, AI-driven listening posts capable of benthic hibernation for months at a time? If a drone can identify a buried Soviet base from 98 fathoms away, it can certainly detect the acoustic signature of a covert insertion team.
In Pressure Depth, human operators still have to strap on their hot-water suits, enter a saturation chamber, and dive to the bottom to deal with the threat manually. But Pressure Depth leaves us with a lingering question. As autonomous platforms become smarter, deadlier, and more persistent, will human intelligence operatives become an endangered species?
Let me know your thoughts in the comments below. How do you see unmanned technology evolving in future Ryanverse novels?
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