underwater

From the ongoing conflict with Iran, to the Ukraine war and hotspots around the world, aerial drones have proven to be extremely dangerous and effective weapons and a mad rush is on to counter them. It is a technology race that makes headlines on a near daily basis. However, a similar but far quieter and less visible threat is emerging below the waves and now the U.S. Coast Guard (USCG) is looking to do more about it.

Faced with a growing threat from uncrewed underwater vehicles (UUVs), the USCG is seeking technology not just to detect these weapons, but to defeat them. Ports and other maritime facilities are vulnerable to this kind of attack vector, and our adversaries surely know it. The effort is being led by the Coast Guard Futures Development and Integration (FD&I) Directorate, which oversees research, modeling and simulation, technology forecasting, and field experimentation. It is part of the service’s role to protect U.S. maritime assets and comes as adversary militaries and non-state actors alike, are developing a wide array of UUVs for surveillance, strike and sabotage.

“UUVs are increasingly used in both public and military maritime operations due to their versatility, stealth, and ability to operate in challenging environments,” the Coast Guard noted in its request for solutions (RFS) posted Friday on the government’s online contracting portal. “However, the proliferation of UUV technology has introduced new threats to maritime security. Malicious actors can employ UUVs for a range of activities, including intelligence gathering, surveillance, smuggling, sabotage of critical infrastructure, and kinetic strikes. The covert nature and advanced navigation capabilities of modern UUVs make them difficult to detect, track, and mitigate using traditional maritime interdiction tactics.”

The most vivid example of this threat took place in December, when Ukraine claimed it used a UUV to strike an Improved Kilo class diesel-electric submarine, in the Black Sea naval stronghold of Novorossiysk. Ukraine’s state security service (SBU) told us at the time they used its Sub Sea Baby UUV to navigate through the harbor and hit the submarine.

It remains unclear how much damage the submarine sustained. However, the incident showed Ukraine was able to slip a UUV into a heavily defended harbor, in daylight, and detonate its warhead next to a prized Russian submarine worth, hundreds of millions of dollars.

The following satellite image showed a view of the submarine after the UUV hit.

Here is a video of the attack:

In an earlier example of these vehicles being used as a weapon, the U.S. Navy found itself having to fire on a threatening Houthi UUV in February 2024, according to U.S. Central Command (CENTCOM).

“Between the hours of 3:00 p.m. to 8:00 p.m. (Sanaa time), Feb. 17, CENTCOM successfully conducted five self-defense strikes against three mobile anti-ship cruise missiles, one unmanned underwater vessel (UUV), and one unmanned surface vessel (USV) in Iranian-backed Houthi-controlled areas of Yemen,” the command stated on X at the time. “This is the first observed Houthi employment of a UUV since attacks began on Oct. 23, [2023].”

Feb. 17 Summary of Red Sea activities

TAMPA, Fla. – Between the hours of 3:00 p.m. to 8:00 p.m. (Sanaa time), Feb. 17, CENTCOM successfully conducted five self-defense strikes against three mobile anti-ship cruise missiles, one unmanned underwater vessel (UUV), and one unmanned… https://t.co/TwR9RUmMMu

— U.S. Central Command (@CENTCOM) February 18, 2024

Hamas used UUVs even before that in an attempt to attack Israeli naval assets in 2021, according to the Times of Israel.

“While the small autonomous underwater drone was still close to the shore, an Israeli Navy vessel destroyed the device, and an IDF aircraft attacked the operatives that launched it in order to thwart the threat,” the military said, according to the outlet.

“Hamas has for years been believed to be developing autonomous submarines,” Times of Israel added. “The Israeli Navy believes that the models in the terror group’s arsenals are guided by GPS and capable of carrying some 30 kilograms (66 pounds) of explosives. Such weapons could be directed against targets both out at sea and along Israel’s coastline.”

The threat from these systems has come a long way. America’s near-peer adversaries are far more advanced in this regard and weapons that can travel great distances undersea, operating on their own, offer a distinct asymmetric advantage. As with Pearl Harbor, it is far more convenient to strike ships in port than to hunt them at sea. China, notably, has invested heavily in uncrewed underwater vehicles for years.

“There are effective technologies with the capability to detect and track UUVs, but few tested and fielded defeat/mitigation systems,” the Coast Guard said in the RFS. 

There are really two areas where these technologies land, in general. Providing early warning and tracking of UUVs over larger areas and coastal and harbor defense, the inner layer where UUVs are arguably most dangerous.

For the U.S., persistent and broad area undersea surveillance coverage has historically been provided by large networks of static hydrophones that are extremely costly to establish, operate, and maintain. They were also designed to detect large submarines, not far smaller UUVs. The U.S. Navy’s Cold War Sound Surveillance System (SOSUS) network is perhaps the best-known example of such a system. Portions of SOSUS do remain in service, but are now used more for scientific research than watching for foreign submarines. SOSUS has been largely supplanted operationally by a mix of fixed sensor arrays, surface ships towing sonar, and processing stations ashore known collectively as the Integrated Undersea Surveillance System (IUSS).

Last year, TWZ highlighted one of many alternatives being developed by industry, Anduril’s readily deployable undersea surveillance system called Seabed Sentry. It uses networks of small and relatively low-cost modular sensor nodes to detect and track undersea threats. You can read more about that system and how it operates in our story here.

Anduril, working with Ultra Maritime’s Sea Spear deployable sonar system, demonstrated the latest iteration of this system during the Navy’s recent Lanternfish exercise, which “brought together the U.S. Navy, United Kingdom Ministry of Defense explosive ordnance disposal units, Royal Australian Navy UUV Operators and defense industry professionals to build seamless interoperability,” according to the U.S. Navy.

The inner layer of defense benefits from ongoing development and evolution, from sensors for detecting divers and objects to marine mammals that can do the same. Still, UUVs offer unique new challenge to contend with.

Last month, Naval Surface Warfare Center (NSWC) Panama City and Unmanned Undersea Vehicle Group (UUVGRU) One “executed a multi-national harbor protection demonstration to show how the advancement of technology plays a crucial role in protecting the Navy’s assets during exercise Baltic Operations (BALTOPS) 2026,” NSWC said.

The demonstration “showcased three emerging technologies including an expeditionary air curtain, an artificial kelp UUV net, and sea water neutralization charges which are designed to counter UUV threats,” the release added.

“The expeditionary air curtain is a rapidly deployable underwater system that is used to protect mission-critical assets below the waterline. The air curtain defends against UUV threats and can be used at Naval bases and military installations as well as ports and harbors by aerating the water to affect the UUV’s depth sensors, acoustic sensors, buoyancy and propulsion.”

“We are testing the air curtain to see how it disrupts and hinders UUV sensors. It is a quick, expeditionary solution because it can be deployed easily,” said Javi Handal, a Senior Electrical Engineer with NSWC Panama City.

He did not provide further details about these systems.

Regardless, the Coast Guard is looking to industry for other options.

“Defeat technologies are an essential piece in the kill chain, as detection is only the first step to stopping the threat,” its RFS explains. “The development and deployment of effective C-UUV defeat solutions will enhance maritime domain dominance (MDD), port security, and critical infrastructure protection, enabling reliable response actions to neutralize UUV-based threats.”

The Coast Guard said it is specifically interested in “solutions that have been tested and demonstrated to be effective in operational settings, with a Technology Readiness Level (TRL) of 5 or higher.”

The Pentagon describes TRL 5 as systems where the “basic technological components are integrated with reasonably realistic supporting elements so it can be tested in a simulated environment. Examples include ‘high fidelity’ laboratory integration of components.”

The requested technologies should be capable of supporting Ports, Waterways & Coastal Security operations, “addressing the unique challenges posed by UUVs in these environments,” the Coast Guard added.

“We are looking for systems that can provide reliable performance in real-world conditions, including but not limited to sensor platforms, kinetic solutions, and integrated response solutions,” the RFS notes. “Respondents are encouraged to submit information on products or systems that are currently available for procurement, have undergone field testing, and are suitable for deployment in port, harbor, and waterway security scenarios. Defeat solutions should be scalable and adaptable for compatibility with existing detection systems and/or various configurations for different ports.”

The Coast Guard is limiting its search to “only systems with an effector or with direct mitigating capabilities, or with detection, tracking, identifying, and mitigating capabilities. Submissions that do not include defeat capabilities will not be considered at this time.”

Interested parties have two weeks to submit their proposals. We reached out to the Coast Guard to find out more details about timelines and budgets and will update this story with any pertinent information provided.

As Ukraine proved last year, the threat from UUVs is real and growing, giving adversaries hard-to-detect and difficult-to-defeat autonomous weapons that can be launched from great distances and potentially operated in concert. The Coast Guard request is the latest example of the U.S. government’s increasing effort to get after this emerging threat.

Contact the author: howard@twz.com

The U.S. Navy sees a future in which uncrewed underwater vehicles (UUV) work together with submersibles loaded with SEALs. The service has already been conducting tests to explore how crewed-uncrewed teaming under the waves might work. UUVs could help extend the operational reach of operators riding in SDVs, as well as help reduce their vulnerability, but there are communications and other challenges still to overcome.

Navy Capt. Mike Linn shared details about the Navy’s plans for teaming UUVs and various types of swimmer delivery vehicles (SDV) with our Howard Altman on the sidelines of the annual SOF Week conference yesterday. Linn currently works within the Naval Special Warfare program office (PMS 340), a division of the Naval Sea Systems Command’s (NAVSEA) Program Executive Office for Unmanned and Small Combatants (PEO USC).

“That is the goal,” Linn said when asked about the Navy’s view of teaming UUVs with SDVs, the latter of which the service also refers to as SEAL Delivery Vehicles.

As it stands now, the main workhorse of the Navy’s SDV force is the Mk 11, which is just under 22 and a half feet long. It is operated by a crew of two and can carry six passengers. Also referred to as the Shallow Water Combat Submersible (SWCS), the Mk 11 is what is known as a “wet” submersible design, where the occupants are exposed to water the entire time during their voyage. The Mk 11, like its predecessors, can be launched and recovered from submerged submarines with specialized Dry Deck Shelters (DDS) attached to their hulls.

The Navy has also acquired several new Dry Combat Submersibles (DCS) in recent years, which feature a pressurized cabin with space for a crew of two and eight passengers. This means the larger DCSs can operate at greater depths than the SWCSs. They also deliver their occupants to the destination dry and relatively warm, helping to reduce operator fatigue and certain potential health risks. The DCS does have the limitation of being too big to fit inside existing DDSs. At least publicly, this is understood to translate to the need for support from a mothership on the surface.

There are multiple UUV designs in the Navy’s inventory today, as well. These are largely torpedo-shaped designs intended to be deployed from and retrieved by vessels riding on the surface or submarines. In recent years, the service has been working to expand its ability to launch and recover UUVs from submerged submarines without the need to send out divers to help. Historically, underwater retrieval of UUVs, in particular, has been a largely manual affair, often conducted via DDS.

In terms of the potential benefits of UUV-SDV teams, “underwater systems like the SDV and UUVs afford reach underwater,” Capt. Linn explained. “So, if you can get somewhere in an SDV and then launch a UUV to go do something, then that would make you more capable.”

“You could extrapolate, just as you would have an unmanned wingman in an aircraft, or a maritime surface co-pilot, the same can be said for underseas,” he continued. “So, if you have an unmanned system with you underwater, then I suppose you can use your imagination.”

“A good example might be a harbor,” he added. “Technology is in a state where passing through the mouth of a harbor, a choke point, is maybe much more well defended. Or it is a choke point, and they don’t want to pass there with a big manned platform. So if you send a smaller unmanned platform through, then that’s pretty logical.”

“It can be an overall risk-reducer,” he further noted. A key mission set for Navy UUVs is scouting ahead for mines and other potential hazards, and otherwise helping commanders establish a better ‘view’ of the battlespace above and below the waves. This could all be especially valuable for SEALs during high-risk missions, including ones being conducted covertly or clandestinely.

Capt. Linn was also candid about the challenges the Navy still has to overcome to make this underwater teaming ability a reality. He described both crewed SDVs and UUVs as being “deaf, dumb, and blind” in terms of their current ability to communicate and coordinate with each other to ensure they are both in the right place at the right time.

“Through-water data transfer is difficult, and so the modality that you choose while remaining survivable is kind of difficult. And, also, in order to do that, you have to have pretty well synchronized systems,” he said. “We’re looking at all ways of transferring data through water. It can be acoustic, [and] there’s light-based transfers.”

There are other questions still be answered around how UUVs teamed with the SDVs would operate, including where the uncrewed companions would be launched from. If the SDVs have to carry them to the launch point themselves, this could present additional challenges.

“You’ve got to consider your volume in the SDV, which is not great,” Capt. Linn noted. “Are you going to strap it to the outside?”

He did confirm that testing is already being conducted to delve deeper into this potential pairing. He said that the Naval Surface Warfare Center Panama City Division (NSWC PCD), headquartered in Panama City, Florida, has been leading the charge.

“I think we’re still years away from having something at the reliability level that they want,” Capt. Linn added. “Again, back to the actual ones and zeros, and the modality of data transmission, [being at the] right time, right place,” and doing all of this “where you have to be survivable, that’s difficult.”

As Capt. Linn has made clear, significant hurdles will need to be cleared before UUV-SDV taming can become a reality. However, there are also real operational benefits that would come from pushing toward this goal.

Contact the author: joe@twz.com

KEY WEST, Fla. — Ruthie Browning dove into the calm, blue water off Key West, Fla., expecting to see “a big, old rock with stuff growing all over it.”

She was on a pilgrimage with other Black divers and community members, visiting sacred sites including one where a British slave ship — the Henrietta Marie — sank 326 years ago.

The vessel had delivered 200 enslaved people from West Africa to Jamaica and was heading back to Britain in 1700 — near the peak of the trans-Atlantic slave trade — when it was swallowed up in the churning waters of New Ground Reef where the Atlantic Ocean meets the Gulf of Mexico.

A concrete marker at the site memorializes the people on that ship.

As Browning and her group prepared to dive in early May, the water was calm. The marker, 20 feet below, was visible from the glassy surface. “I thought I’d look at it, pay my respects and that’ll be that,” she said.

But something unexpected happened. Tears filled her eyes. She gently told herself: If you can be quiet, maybe they will speak.

Staring at the monument, which is now a small living reef covered in corals and sponges, she felt her ancestors’ words: “My daughter, we’re so glad you’re here.”

Overwhelmed, Browning lingered by the marker bearing the words: “Henrietta Marie. In memory and recognition of the courage, pain and suffering on enslaved African people. Speak her name and gently touch the souls of our ancestors.”

She felt submerged in gratitude.

“Without their stamina, their spirit and survival, I wouldn’t be here today. None of us would be here today,” she said.

Pilgrimages aren’t meant to be easy

For the pilgrims in Key West, the gathering was an act of devotion, a quest for connection with their roots and for spiritually nourishing generations to come. They had tried to dive to the marker last summer, but the water was too choppy.

“The ancestors were not smiling down on us then,” said Jay Haigler, master diving instructor with Underwater Adventure Seekers, the world’s oldest Black scuba diving club. “This year was different.”

Such a pilgrimage was never meant to be easy, said Michael Cottman, who has written two books about the Henrietta Marie and was part of the National Association of Black Scuba Divers that installed the marker in 1992.

Cottman believes the site contains “spiritual turbulence.”

“Even if it wasn’t carrying enslaved people, it embodies the oppression of our people,” he said.

The group organized an annual pilgrimage in the 1990s, but it didn’t continue. The latest trip was spurred by an underwater interview project proposed by Stanford University anthropologist Ayana Omilade Flewellen, who serves on the board of Diving With a Purpose, a Black scuba diving nonprofit dedicated to documenting slave shipwrecks.

The submerged interviews also helped her connect as a pilgrim, Flewellen said. “I felt a kind of tenderness in my heart.”

The spiritual experience helped her process a traumatic history rooted in death and suffering.

“It’s hard to attach your life with this history,” she said. “The only way I could do that was turn toward what the divers were experiencing on this pilgrimage. That’s where it all bloomed and blossomed.”

Ancient ritual at African refugee cemetery

The pilgrims also gathered on land. At Higgs Beach on the south side of Key West, they visited a memorial and burial ground for 297 African refugees who died in 1860 after being rescued by the U.S. Navy from three slave ships — Wildfire, William and Bogota. Over 1,400 refugees were housed by the government in a compound and provided food and medical care, said Corey Malcom, the Florida Keys History Center’s lead historian.

While many were sent back to Africa, hundreds died due to the horrific conditions on the ships, he said.

Largely forgotten for decades, the grave site was discovered by historians and geologists using ground-penetrating radar. In 2010, a large pit containing 100 more bodies was located at a community dog park across the street. The area is now fenced off, Malcom said.

On Saturday, pilgrims met at the cemetery and held an emotional libation ceremony, a sacred, ancient ritual rooted in Afro-Caribbean spiritual tradition. One by one, group members tearfully thanked their ancestors and poured white rum on the beach. The clear spirit is believed to act as a messenger, inviting ancestral souls for their blessings.

“To honor your ancestors and the road they’ve traveled is very, very important because we’re all connected,” said Addeliar Guy, one of the elders and an avid diver.

Underwater monument represents a living history

Joel Johnson trained for weeks for his first open-water dive at the Henrietta Marie site. Johnson, the president and CEO of the National Marine Sanctuary Foundation, said what surprised him as he approached the monument was the vibrancy surrounding it. Fish darted among the corals that swayed with the currents; shells rested on the sandy bottom.

Conservation and protecting these habitats also preserve the history below the waves, Johnson said.

“This was not a place of death, but a place of life,” he said. “I didn’t feel like I was grieving for my ancestors. I felt like I was in the stream of history, recognizing that I’m a part of that. It made me happy.”

While underwater, Michael Philip Davenport, president of Underwater Adventure Seekers, was inspired to create art showing ancestors emerging from the monument.

“Their spirituality is still in that space,” he said. “I was feeling their lives and their tragedy.”

Dr. Melody Garrett, an anesthesiologist, started training with Diving With a Purpose in 2011 and has gone on missions to find the Guerrero, a Spanish pirate ship that wrecked in 1827 while carrying 561 enslaved Africans.

“A pilgrimage like this is so important now more than ever because there is an effort to cover up, rewrite and change history,” she said. She cited the Trump administration’s moves to remove references to slavery and Black history at National Park Service sites and federal museums, labeling it as divisive “anti-American propaganda.”

For Garrett, seeing these pieces of history gives her a strong sense of identity as an American, as the nation prepares to celebrate its 250th birthday.

“Black people have been here since before this country’s inception, longer than many other people have,” she said. “This is our country.”

Exhibit displays shackles used in slave trade

Remnants of the Henrietta Marie’s wooden hull are embedded at the site under layers of sand. The shipwreck was discovered in 1972 by treasure hunter Mel Fisher, but it wasn’t until 1983 that hundreds of intact items were recovered. Only a few slave ships were found out of the 35,000 used to transport over 12 million enslaved Africans; most vessels were intentionally destroyed to hide the illicit trade.

The artifacts, which occupy an entire floor of the Mel Fisher Maritime Museum in Key West, include over 80 sets of iron shackles, many of them child-size.

When Kory Lamberts first walked over wooden planks in the exhibit, they unexpectedly creaked.

“It was visceral,” he said. “It took me to a place. It also tells me that these were young people — children. These are baby shackles. There’s no sugarcoating it. The truth really hits you.”

While in Key West, Lamberts — who runs a nonprofit to make aquatics more equitable — said he brought back fish from the Henrietta Marie site, which he imagines would have absorbed the DNA of the ancestors. The group ate that fish for dinner the night after the dives — like a sacrament.

“I don’t practice a faith, but isn’t this what people are doing every Sunday at church?” he asked. “I wasn’t just bonded with this site through the experience of being there, but at this molecular level with a full circle moment of connection with myself and my history.”

Bharath writes for the Associated Press.