YC-backed DAIVIN is building tankless dive gear around water electrolysis

Why it matters

DAIVIN is trying to exchange stored breathing gas for electricity. Success depends on proving a compact electrolyzer can control gas mixtures and survive failures as reliably as established dive systems.

Leo Kankkunen (@se4lion) is using Y Combinator's backing to develop dive gear that generates breathing gas from water, an attempt to replace compressed-gas cylinders with electrolyzers and batteries worn by the diver.

https://www.youtube.com/watch?v=r5HfL8Bw0dw

Kankkunen founded DAIVIN in Helsinki in 2025 after concluding that the logistical constraints he encountered as a diver could be treated as an electrical engineering problem. DAIVIN joined Y Combinator's Winter 2026 batch as a one-person operation and published its launch pitch roughly seven months ago.

The founder arrived at the problem after years working around high-voltage infrastructure. Kankkunen earned an electrical and automation engineering degree from Centria University of Applied Sciences, where his 2022 thesis examined the management of electrical work on railway electrification projects. He later completed a master's thesis at LUT University on regulatory compliance in Finnish railway electrification. Kankkunen also holds Finland's S1 electrical qualification, whose statutory requirements cover high-voltage systems and the supervision of electrical work.

That background fits DAIVIN's central bet: a diver can carry enough electrical energy to split surrounding water into oxygen and hydrogen at the rate needed to breathe. Kankkunen has posted a video he describes as a prototype dive, though the footage does not establish the system's gas-production rate, depth capability or endurance.

What DAIVIN says it has built

DAIVIN's proposed system puts three electrolyzers in a vest and moves the batteries to a belt that replaces a conventional weight belt. DAIVIN says redundant electrical paths would keep gas flowing after an individual wire or circuit failure.

A DAIVIN product sheet lists a 20-by-40-by-5-centimeter unit weighing 5 kilograms, including two batteries. DAIVIN claims each battery could support between 30 minutes and one hour of diving. The same sheet lists a target depth of 150 meters, pressure-based automatic adjustment and a hydrogen breathing mixture intended to reduce decompression time.

DAIVIN labels the entire document conceptual and says it does not describe a final product. The specifications also differ from Kankkunen's YC launch pitch, which claimed the system could enable dives to 200 meters. Those figures remain DAIVIN's targets rather than independently validated operating limits.

The distinction matters because electrolysis itself is established technology. Researchers have demonstrated compact electrochemical systems capable of producing high-purity oxygen at rates relevant to medical use. DAIVIN's challenge is integrating gas production, power storage, pressure management, breathing-loop controls and redundant life support into equipment that can survive a diver's workload and an underwater failure.

Depth turns oxygen generation into a gas-control problem

Generating oxygen is only one part of the system. Its concentration must change with depth because the physiological effect depends on oxygen partial pressure. Divers Alert Network guidance notes that excessive oxygen partial pressure can cause central nervous system toxicity and underwater convulsions. Deep diving therefore relies on carefully selected breathing mixtures rather than pure oxygen.

DAIVIN proposes using the hydrogen produced by electrolysis as part of the breathing mixture, avoiding nitrogen narcosis and reducing reliance on helium. Hydrogen has a history in experimental deep-diving research, including work documented in U.S. Navy literature, but it introduces another control problem: mixtures containing hydrogen and oxygen can ignite across a broad range of concentrations.

A production system would have to continuously regulate oxygen partial pressure, keep carbon dioxide from accumulating, isolate or meter hydrogen safely, and provide a bailout supply if power or electrolysis stops. DAIVIN's launch materials describe redundant gas generation and a battery-based bailout mode. They do not provide test data for gas composition, respiratory workload, thermal behavior, seawater contaminants or operation under pressure.

The depth claims also place DAIVIN beyond ordinary recreational diving. NOAA describes dives below 40 meters as technical operations requiring specialized gas mixtures, equipment and training. At 150 meters, DAIVIN would be competing with mature surface-supplied and closed-circuit systems designed around extensive procedures, backup gas and monitored decompression.

Commercial divers are the first target

Kankkunen has been seeking conversations with commercial and offshore divers, a more plausible initial customer group than recreational consumers. Cylinder transportation, gas blending and support vessels create direct costs for remote underwater work, giving professional operators a reason to evaluate a lighter system if DAIVIN can demonstrate equivalent reliability.

Commercial buyers will also demand evidence that goes far beyond a prototype dive. Life-support hardware must perform through component failures, changes in workload and rapid depth transitions. A tank stores a finite supply of gas, but its remaining volume can be measured and an independent cylinder can serve as a backup. DAIVIN replaces that known constraint with dependence on batteries, sensors, electrolyzers and control software.

Kankkunen's larger plan extends the same architecture to altitude, emergency response and space, where oxygen generation from water is already an established concept. Diving is the harder proving ground because the device must operate on a moving person, under pressure, with immediate consequences if gas production falls behind demand.

DAIVIN has framed oxygen as an energy problem rather than a transportation problem. The prototype is the opening evidence for that thesis. Turning it into dive equipment will require DAIVIN to show that a compact electrical system can match the predictability and redundancy of the tanks it is designed to remove.