Pasadena, United States - February 24, 2025 In a laboratory tank, an innovative underwater robot is rewriting the rules of aquatic travel. Dubbed CARL, this palm-sized autonomous vehicle is making waves by harnessing the power of water currents to propel itself with remarkable efficiency. Designed by engineers Peter Gunnarson and John O. Dabiri, CARL represents a breakthrough in navigating the unpredictable flows that challenge underwater and aerial vehicles alike. Traditional vehicles expend significant energy battling gusts and currents to stay on course. CARL, however, takes a different approach, riding these flows like a surfer catching a wave. Equipped with ten motors for movement along all three axes and an onboard inertial measurement unit, the robot uses a straightforward yet ingenious algorithm. When the acceleration in the crossflow direction surpasses a set threshold, CARL swims with the force, effectively “surfing” the water’s vortices to reach its destination. The robot’s prowess was put to the test in a 5-meter-long, 1.5-meter-deep tank, where vortex rings were created by a wall-mounted thruster. In these controlled conditions, CARL surfed from one end of the tank to the other, using just one-fifth of the energy required by a robot lacking its specialized programming. This dramatic reduction in energy consumption highlights the potential of the technology. Gunnarson and Dabiri believe CARL’s success with this prototypical flow structure is only the beginning. They suggest that with further refinement, the technique could be scaled up, enabling autonomous vehicles to interact with background flows in real-world environments. Such advancements could significantly boost the efficiency of underwater robots, opening new possibilities for exploration, research, and beyond. For now, CARL’s smooth ride through the tank offers a tantalizing glimpse of a future where machines work with nature, not against it.