Imagine a robot that can dive beneath the ocean, chase underwater targets, then burst out of the water and soar through the sky like a bird. It may sound like science fiction, but engineers from MIT and EPFL in Switzerland have turned this idea into reality.
Inspired by birds such as puffins, loons, gulls, petrels, and kingfishers, researchers have created a remarkable robotic vehicle that can both swim underwater and fly through the air. This new invention could transform ocean exploration, environmental monitoring, and marine research while helping scientists better understand how diving birds perform their incredible aerial and underwater maneuvers.
The groundbreaking research has been published in the prestigious journal Science.
Nature Inspired the Perfect Design
Many birds are experts at moving between two completely different environments—air and water. Birds like puffins and loons can fly long distances, dive into the ocean to catch fish, swim underwater with amazing speed, and then return to the sky.
These birds have evolved over millions of years to master this difficult transition. Engineers wondered if a robot could achieve the same ability.
That challenge led researchers at the Massachusetts Institute of Technology (MIT) and EPFL in Lausanne, Switzerland, to develop the Flapping-Wing Aerial-Aquatic Vehicle (FAAV).
The robot weighs less than 300 grams (10.6 ounces), making it incredibly lightweight while still capable of operating in both air and water.
Why Flying and Swimming Is So Difficult
Designing a robot that works in both environments is far more challenging than it sounds.
Water is nearly 1,000 times denser than air. A wing that performs perfectly in the sky may struggle underwater because of the much greater resistance.
Similarly, movements that help a robot swim may not generate enough lift for flight.
Because of these huge differences, engineers have traditionally designed separate flying drones and underwater vehicles.
The MIT team wanted to break this limitation by creating a single machine capable of doing both.
Learning from Diving Birds
To solve the problem, researchers carefully studied the flight mechanics of diving birds.
They examined scientific studies on:
Puffins
Petrels
Kingfishers
Loons
Gulls
Other aquatic birds
They discovered interesting patterns.
Small diving birds flap their wings about 10 times every second while flying, but reduce that speed to around 4 flaps per second underwater.
Larger birds flap slightly slower because of their wider wings.
Using these observations, the engineers designed their robot to mimic the same natural movements.
A Bird-Like Robot
The FAAV closely resembles a bird.
It includes:
A lightweight central body (fuselage)
Two flexible flapping wings
A movable tail
Waterproof electric motor
Rechargeable battery
Instead of using spinning propellers like traditional drones, the robot flies by flapping its wings, just like a real bird.
Inside the body, a waterproof motor powers a crankshaft that moves the wings up and down.
The wings themselves are made from thin flexible membranes coated with hydrophobic nanoparticles, which help repel water so the robot can quickly transition into flight after leaving the surface.
The tail can change its angle during operation, allowing the robot to climb into the air or dive underwater.
Testing Different Wing Designs
The engineers built three different wing sizes:
Small (60 cm)
Medium (80 cm)
Large (100 cm)
Each wing set was tested under various conditions.
Experiments were first conducted inside a controlled water tank before moving to Lake Geneva in Switzerland.
During each test, the robot started about half a meter underwater.
Researchers adjusted:
Wing size
Flapping frequency
Tail angle
They then observed whether the robot could successfully swim upward, break through the surface, and continue flying.
The Best Wing Combination
After numerous tests, one design clearly stood out.
The medium-sized wings produced the best overall performance.
Researchers found that flexibility was extremely important.
The wings needed to be:
Flexible enough to reduce water resistance underwater
Strong enough to generate lift in the air
Finding the perfect balance allowed the robot to perform efficiently in both environments.
Fast Underwater and Fast in the Air
Performance results were impressive.
Underwater, the robot reached speeds close to 1 meter per second while flapping its wings about 5 times each second.
Once airborne, it accelerated to approximately 6 meters per second, using nearly the same wing-flapping frequency.
These values closely match the swimming and flying behavior observed in real diving birds.
Escaping the Water
One of the biggest engineering challenges was helping the robot leave the water.
The team discovered that the robot needed to point upward at an angle of about 70 degrees while approaching the surface.
This angle prevented the wing tips from hitting the water during takeoff.
If the angle became too steep, the robot would lose balance and fall backward.
With the correct angle, the robot smoothly launched from underwater into flight.
Surprisingly, It Doesn't Need Feet
Perhaps the most surprising discovery came during takeoff.
Real birds such as ducks and puffins usually paddle with their feet while flapping their wings to gain enough momentum to leave the water.
The researchers expected their robot would need a similar mechanism.
Instead, they found that the robot could launch directly from underwater using only its wings and tail.
No paddling legs were necessary.
This unexpected result simplifies the robot's design while making it lighter and more efficient.
Future Ocean Exploration
The researchers believe this technology could revolutionize marine science.
Current ocean research often depends on expensive ships or separate underwater robots and aerial drones.
A hybrid robot capable of flying and swimming could perform both tasks alone.
Scientists imagine launching the robot from a boat or even directly from the shoreline.
The robot could:
Fly to remote ocean locations
Dive underwater to collect water samples
Measure temperature and pollution
Monitor coral reefs
Observe whales and marine life
Inspect ports, offshore platforms, or icebergs
Return quickly with collected data
Because the robot can travel rapidly through the air, it could complete many missions at a fraction of the cost of traditional methods.
Even Smarter Robots Ahead
The team is already working on improving the robot.
Future versions will include wings that can rotate as well as flap, providing even greater control during flight and swimming.
Researchers also plan to test the vehicle in more realistic environments, including:
Strong winds
Ocean waves
Choppy water
Turbulent weather conditions
These improvements could make the robot ready for real-world scientific missions.
A New Era of Bio-Inspired Robotics
This project demonstrates how nature continues to inspire engineering breakthroughs.
Rather than inventing entirely new solutions, scientists looked at birds that have already mastered one of nature's most difficult challenges—moving effortlessly between water and air.
By copying these biological strategies, the team has built a robot that performs an ability few machines have ever achieved.
The flapping-wing aerial-aquatic vehicle represents a major step toward multi-environment robots capable of exploring places humans and traditional machines struggle to reach.
As the technology continues to improve, these bird-inspired robots could become valuable tools for oceanographers, marine biologists, environmental scientists, and coastal communities. One day, fleets of these lightweight robotic birds may routinely fly across the sea, dive beneath the waves, collect important scientific data, and return to the sky—bringing us closer than ever to understanding and protecting Earth's oceans.
Reference:
- Raphael Zufferey et al.
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