Kairox Systems, a three-person San Francisco startup backed by Y Combinator, is developing Tempest, a fixed-wing vertical-takeoff drone designed to fly, dive and resurface. The company's website places the aircraft at technology readiness level 4, a stage at which components have been validated in a laboratory but the full system has not been proven in realistic conditions.
The timing is notable. Navies, cable operators and ocean scientists are all chasing unmanned systems that can cross the waterline. Kairox's homepage shows a 50 km range and a payload of about 1 pound, but its Tempest page says range, endurance, depth and speed are "not published," and there is no independent coverage of a public in-water demonstration.
What the company says it is building
"We make drones that can fly and swim," the website states. Its concept of operations moves from air transit to water entry, then subsurface travel, then breach and egress.
Tempest is described as a hybrid aerial-underwater vehicle with a "pressure-vessel core," "GPS-denied autonomy," modular payloads and what the site calls an "attritable" cost profile, meaning cheap enough to lose without much pain. The homepage lists a Group 1 classification (the Pentagon's category for the smallest drones), a payload of about 1 pound and a range of "50 km." That last figure reads as marketing, and the company's own Tempest page undercuts it by saying specifications are "not published." The same page says "second prototype testing in progress."
In a late-October LinkedIn update reposted by CEO Joel Santiago Baretti, the company wrote: "Kairox Systems is officially backed by Y Combinator. Drones that can fly and swim are the next evolution of unmanned systems. Our flagship platform, Tempest, is currently undergoing rigorous testing."
Team and funding
The site names Santiago Baretti as chief executive, Alex Rice as chief technology and financial officer, and Jorge Cavazos-Cuellar as chief operating officer, and it notes the founders' MIT backgrounds. Y Combinator's founder directory lists the company in its F26 batch with a team of three and describes Cavazos as an MIT alumnus. LinkedIn shows 2 to 10 employees and a 2026 founding.
Kairox has not announced how much it raised. Dealroom lists a "Y Combinator $125k seed (Sep 2026)," but that figure should be considered indicative until the company or Y Combinator confirms it.
A market with disputed numbers
No major analyst firm appears to break out amphibious single-platform drones as a category. The broader market for unmanned underwater vehicles, or UUVs, varies widely depending on who is counting.
MarketsandMarkets put it at $6.91 billion in 2026, rising to $19.22 billion by 2031, a compound annual growth rate of 22.7%. Fact.MR, in a report posted Oct. 30, estimated $5.7 billion in 2026 and $18.4 billion by 2036. Mordor Intelligence pegged 2025 at $4.01 billion, reaching $5.58 billion in 2030, or 6.83% annual growth. The Insight Partners, which combines underwater and surface vehicles, forecast $4.65 billion in 2025 and $15.45 billion by 2034.
Growth rates that differ by a factor of three suggest the forecasts say more about each firm's definitions than about the market itself.
Defense demand
The AUKUS Pillar II fact sheet, covering the security pact among the U.S., Britain and Australia, prioritizes unmanned undersea vehicles and their payloads, including drone deployment. It projects 2027 starts for UUV payload deliveries. The three countries ran "Maritime Big Play" trials in 2026.
"The objective is straightforward. Identify areas where working together delivers an operational advantage that no one nation could achieve as efficiently on its own," Michael Dodd, assistant secretary for critical technologies at the Pentagon's research and engineering office, told USNI News.
Cmdr. Ed Smith, a Royal Navy principal warfare officer for the underwater environment, told USNI that cheaper systems run by fewer people allow a kind of "mass" that crewed vessels could not achieve.
NATO's REPMUS 2026 exercise drew 1,500 participants from 36 navies, according to the alliance's Allied Command Transformation. Mine-countermeasure drills paired aerial and autonomous underwater vehicles using STANAG messaging, NATO's standardized data formats.
Cables and climate
TeleGeography counts roughly 607 in-service undersea cable systems spanning more than 1.5 million kilometers. TechRadar reported on Russian vessels loitering over cables linking Europe and the U.S. Governments are responding: the research cites a British proposal to replace the 1885 Submarine Telegraph Act and a European Union Action Plan on Cable Security.
Scientists have their own appetite for such machines. The Woods Hole Oceanographic Institution reported on May 13 that an autonomous underwater vehicle detected biodiversity hotspots. NOAA scheduled a demonstration of integrated data from underwater vehicles, remotely operated vehicles and ships for Oct. 29 to Nov. 16. The Associated Press reported June 4 that the EU is expanding its use of underwater drones and satellites for ocean monitoring while the U.S. weighs cuts.
Competitors and incumbents
Public prototypes of fixed-wing hybrids are few, the research found. SubUAS, a Rutgers spin-out, markets its Naviator as among the most mature aerial-aquatic hybrids and held live demonstrations in April in St. Petersburg. In India, AquaAirX unveiled its Avataar amphibious drone in March, and one outlet reported a TRL-6 claim.
"Why should UAVs operate only in the air? Why can't the same system transition underwater as well?" the AquaAirX founders told NDTV.
Bigger players are approaching from the water. Lockheed Martin unveiled its Lamprey UUV on Feb. 10, a vehicle that can attach to ships and launch aerial drones and decoys. Anduril Australia delivered its first Ghost Shark extra-large autonomous underwater vehicle in January. Academia is also working the problem: MIT and EPFL published research on July 9 describing a flapping-wing robot that swims and flies out of the water.
Regulatory hurdles
The Federal Aviation Administration's final rule on beyond-visual-line-of-sight flights was still unpublished as of Sept. 4, and Remote ID requirements remain in force. Section 232 duties on drone imports took effect Sept. 3, with tariffs of 10% to 100%. Federal Communications Commission actions restrict foreign-made drones and critical components, with exemptions for Blue UAS and domestic end products until Jan. 1, 2027. Together, the rules push buyers toward domestic or allied supply chains.
What to watch
For now, Kairox owes the market evidence from the water. The research advises treating mission claims as developmental until customer trials or procurement results appear, and the most immediate proof point would be the specifications the company has so far withheld.
The broader ambition has been voiced more plainly by academics. Raphael Zufferey, an MIT assistant professor of mechanical engineering, described it in MIT News: "Our dream vision is for oceanographers, marine biologists, and members of coastal communities to launch this robot from a boat, or from shore, and it would fly close to the area of interest, such as an iceberg or a port facility, or over a pod of whales."
