Is it possible for humans to run on water? While some animals appear to defy gravity on liquid surfaces, humans cannot run on water naturally or unaided. This is due to the physical laws governing liquids and human physiology, though certain creatures possess remarkable adaptations that allow them to accomplish this feat.
The Physics of Walking on Water
The primary reason humans cannot run on water stems from fundamental physical principles. When a human foot impacts the water, the body’s weight exerts too much force for the water to support. While water molecules exhibit cohesion, creating surface tension, this force is only strong enough for very lightweight objects. A human’s substantial mass generates downward pressure that instantly breaks through this delicate surface layer.
Buoyancy, the upward force exerted by a fluid, also plays a role, but it primarily enables floating, not running. While the human body is close to the density of water, allowing many people to float, this static support is insufficient for the dynamic, forceful interaction required for running. The force needed to push water downwards with enough speed to generate hydrodynamic lift, similar to how a boat planes, is enormous. Estimates suggest a human would need to run at speeds approaching 67 miles per hour (approximately 30 meters per second) to generate sufficient force, a pace far beyond human athletic capability. This would also require generating mechanical power up to 15 times greater than what a trained athlete can produce.
Nature’s Water Walkers
While humans cannot run on water, several species in nature exhibit this extraordinary ability through specialized adaptations. Water striders, for instance, are small insects that glide effortlessly across pond surfaces. They exploit surface tension, aided by their lightweight bodies and uniquely structured legs. Their long, slender legs are covered in thousands of microscopic, hydrophobic hairs called microsetae, which repel water and trap air, preventing them from breaking the surface film. These adaptations allow water striders to distribute their minimal weight over a large area, creating small dimples in the water’s surface without breaking through.
Another impressive water-walker is the basilisk lizard, also known as the “Jesus Christ lizard.” This reptile runs bipedally across water to escape predators. Its large hind feet possess specialized skin fringes or webbing that unfurl upon contact with the water, dramatically increasing the surface area.
The lizard executes a rapid “slap, stroke, and recovery” motion, forcefully slapping the water to create an air pocket and then quickly stroking backward to generate forward thrust before the pocket collapses. This requires immense speed, with basilisks running up to 15 miles per hour (24 kilometers per hour) and taking as many as 20 steps per second. Smaller, juvenile basilisks are more adept at this feat due to their lighter weight.
Human Limitations and Theoretical Possibilities
Based on the physics involved, natural human water running remains impossible due to our body mass, limited foot surface area, and insufficient muscle power. Even the world’s fastest sprinters cannot generate the speeds and power required to stay atop the water.
Despite these limitations, theoretical discussions and experiments have explored hypothetical scenarios. Some suggest that if a human could achieve extreme speeds, similar to skipping a stone, they might briefly run on water. Another concept involves specialized footwear, such as massive buoyant shoes or fins, though these would be cumbersome and impractical for actual running. Research simulating reduced gravity environments has shown that humans could run on water with small fins at gravitational levels similar to the moon. These possibilities remain largely in the realm of science fiction or highly controlled experimental conditions, underscoring the natural impossibility for humans to run on water.