On July 15, 2026, engineers from EPFL and MIT published results in Science describing a robot that can fly through air and swim underwater using the same flapping wings. The vehicle — weighing less than 300 grams — takes inspiration from diving birds such as puffins, loons, and petrels.
Key takeaways
- FAAV (flapping-wing aerial-aquatic vehicle): mass under 300 g, wingspan 80 cm
- Swimming speed ~1 m/s at 5 Hz, flight speed ~6 m/s at a similar flapping frequency
- Wings made of a flexible membrane coated with hydrophobic nanoparticles to repel water
- Water-to-air transition at 70 degrees pitch angle — no feet or additional limbs required
- Published in Science (DOI: 10.1126/science.aeb6744)
The diving bird as an engineering blueprint
Of the roughly 10,000 known bird species, only about 100 can both fly and swim. Puffins, loons, auks, and petrels navigate two environments with radically different physical properties: water is over 800 times denser than air, requiring fundamentally different wing dynamics in each medium. That challenge has fascinated bioinspired roboticists for years.
Raphael Zufferey, lead author and assistant professor of mechanical engineering at MIT, started the project as a postdoctoral researcher at EPFL under the supervision of Dario Floreano (LIS) and Auke Ijspeert (BioRob). He completed the work at his AURA Lab. Tests were carried out in a laboratory water tank at EPFL and in Lake Geneva.
Wing mechanics and water takeoff
The robot's body houses a battery and a waterproof electric motor driving a crankshaft that flaps the wings at pre-set frequencies. A motorized tail controls pitch angle for diving or climbing.
In water the robot reaches ~1 m/s while flapping at 5 Hz — comparable to actual diving birds. In air the same frequency yields ~6 m/s. The key finding is the absence of feet: to leap from water, the robot simply pitches to 70 degrees so the wingtips clear the surface. Zufferey notes this is the first time a robot has exited water using wings alone.
Material and size matter
The 80 cm wings are made of a thin flexible membrane coated with hydrophobic nanoparticles?hydrophobic nanoparticles: nano-scale particles coated on the wing surface that repel water — the wing does not absorb moisture and retains aerodynamic properties after surfacing. Flexibility is a deliberate trade-off: in water the wings need to deform to reduce flapping amplitude and hydrodynamic drag. In air they must be stiff enough to generate lift. The team tested multiple wing sizes and found 80 cm to be optimal for this configuration.
Applications and next steps
The researchers envision deployment in ocean science. A vehicle launched from shore or a boat could fly to difficult-to-reach areas — an iceberg, a shipping port, or a whale pod — dive for a water sample or measurement, and fly back at a fraction of the cost of traditional research vessels.
Near-term development plans include adding wing rotation capability — currently the wings only flap up and down — and testing under turbulent conditions: choppy water and strong winds.
Why this matters
Most autonomous vehicles specialize in one environment. Drones fly. AUVs?AUV: Autonomous Underwater Vehicle — a robot specialized exclusively for underwater operation, with no aerial capability swim. AMRs?AMR: Autonomous Mobile Robot — a ground-based autonomous mobile robot (e.g. in warehouses); it plans its own path and avoids obstacles, but is confined to a single environment — land drive. The transition between environments — especially between air and water — has belonged to birds, not machines. FAAV demonstrates that the right combination of materials, geometry, and kinematics can solve this problem without complex transformation mechanisms.
From a robotics perspective the significance lies in simplicity: one propulsion system (wings plus tail) for both environments, no active transition mechanism, no feet, no separate launch motor. Publication in Science provides peer-reviewed confirmation rather than just a demo video.
The potential in environmental monitoring is concrete. Assessing coral reef health, sampling water near a leaking oil platform, monitoring marine ecosystems — these are tasks where an air-water hybrid could be substantially cheaper and safer than current methods.
What's next
AURA Lab (MIT, Raphael Zufferey) plans to add wing rotation capability for improved directional control beyond tail-only steering.
Turbulent-condition testing (choppy water, wind) is the next phase before oceanographic field deployment.
The team plans collaboration with oceanographers and marine biologists for pilot sampling missions.
