# If humans ran fast enough, could we run across water? **URL:** \ **Category:** Factual Questions\ **Created:** [August 21, 2016, 11:45pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585 "2016-08-21T23:45:44Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 26, 2016, 2:50pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/21 "2016-08-26T14:50:43Z")
So, **watchwolf** , what you found is that if the human has almost no lift, then its trajectory will be almost the same as if it had no lift? I fail to see how that’s an interesting result at all, and it’s certainly not a relevant result to the question at hand, which concerns a human with a large amount of lift. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [August 26, 2016, 3:26pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/22 "2016-08-26T15:26:17Z")
> [@boffking](#): > > **If humans ran fast enough, could we run across water?** … [snip] > [@Chronos](#): > > So, **watchwolf** , what you found is that if the human has almost no lift, then its trajectory will be almost the same as if it had no lift? I fail to see how that’s an interesting result at all, and it’s certainly not a relevant result to the question at hand, which concerns a human with a large amount of lift. Right, the **Factual Answer** to the OP’s **General Question** is no, humans cannot run across water. **Zack29’s** citation states this, it makes common sense and I’ve experimented up at the lake the other day. > [@](#): > > Notwithstanding various internet hoaxes, humans are apparently incapable of walking or running on water. In their classic study (Glasheen, McMahon; 1996) of the Basilisk lizard, Glasheen and McMahon calculate the unsurprising result that humans are far too big and weak to splash their feet hard enough to hold their weight. According to their estimates (_ibid._), humans would be able to run on water only if they were able to slap water at speeds \>30 m/s, which they estimate would require about 15 times a human’s available muscle power. Humans do not have enough lift, there’s no “if” about it. **Bucketybuck** presents the better counter-argument; it’s not running, it’s momentum; certainly better than humans are actually 15 times stronger than they really are. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [August 26, 2016, 4:16pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/23 "2016-08-26T16:16:39Z")
> [@watchwolf49](#): > > Right, the **Factual Answer** to the OP’s **General Question** is no, humans cannot run across water. No, that is only the factual answer to a limited reading of the OP’s subject line. The full OP however includes the salient lines: “I have heard people say that if we ran at some insanely high speed(I’ve heard both 70 and 200 mph) , we could do it too. Is there s hypothetical speed where this would happen?” The answer to that is “Some scientists working on a model for how Basilisk lizards run on water have estimated that humans would have to run at 67 mph to run on water, so the 70 mph figure isn’t far off.” If we want to be super cautious we may include “But that is of course impossible”, but that caveat doesn’t seem to be necessary for the OP based on his full question for a hypothetical speed. ---
**Author:** ![Cayuga](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Cayuga](https://boards.straightdope.com/u/Cayuga)\ **Post date:** [August 26, 2016, 6:40pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/24 "2016-08-26T18:40:04Z")
The Flash does it all the time. If it’s in a comic book, it must be true, right? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 26, 2016, 7:18pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/25 "2016-08-26T19:18:39Z")
**watchwolf** , the question was how fast we would need to be. All your answer amounts to is that the necessary speed is greater than what we’re capable of. But everyone in the thread already knew that. We’d like a more detailed answer, like those already given by more knowledgeable posters before your answer. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 26, 2016, 11:41pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/26 "2016-08-26T23:41:41Z")
Yup, the question in the OP acknowledges that it would be a superhuman feat. The question is not ‘can ordinary humans do it’, but ‘could they do it if they were able to run fast enough, and if so, how fast is that?’ ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [August 26, 2016, 11:52pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/27 "2016-08-26T23:52:56Z")
> [@Urbanredneck](#): > > Are we talking flat, quiet water or active water like in the oceans with the big waves? > > With the waves one would need to step on each one which would be a trip hazard. I don’t know why, but the idea of waves as a “trip hazard” cracks me up. Thanks, **Urbanredneck**. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [August 27, 2016, 1:41pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/28 "2016-08-27T13:41:34Z")
> [@Mangetout](#): > > Yup, the question in the OP acknowledges that it would be a superhuman feat. The question is not ‘can ordinary humans do it’, but ‘could they do it if they were able to run fast enough, and if so, how fast is that?’ What does horizontal speed have to do with vertical lift? The citation in post #4 had the humans wear flippers scaled to be proportional to the lizard’s feet and then they suspended the humans from the ceiling to simulate 20% gravity over a pool of water. There was no lateral speed involved, the humans created enough lift by running in place, 0 mph. I haven’t read the reference concerning the lizard, but I think it fair to assume the lizard started out by running, to chase down prey and escape predators. It then adapted to running on water to better chase down prey and escape predators by evolving flipper feet and perhaps a highly specialized muscle configuration. It’s about the rate of slapping the water, which isn’t dependent on forward speed for humans. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 27, 2016, 4:06pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/29 "2016-08-27T16:06:46Z")
It’s a good point that forward speed isn’t the same as vertical lift, but I think it’s implied that a super-human able to run at 70mph would be doing so precisely because they were able to exert more force using their legs. More force imparted on the water provides more reaction. There’s another thought experiment that I think works here: When I was younger and fitter, I could tread water and exert enough force doing so that I could raise my upper body above the water surface, for a short (but sustained) time - to a level where the water line was somewhere below my nipples, but above my navel. If I was endowed with greater strength, I would have been able to rise and remain further out of the water. If I had superhuman strength, I would have been able to go further, and so on - like a dolphin [tail-swimming](https://www.youtube.com/watch?v=Cb4lC0F4cPw). It is a game of diminishing returns, as the more of your body is out of the water, the less is able to act upon the water. Now, I know humans are not dolphins - and the area of a dolphin’s tail fluke is greater than the surface area of human feet, but these are all just scale factors - if you have smaller area, you need more force (or if you have more force available, you need less area). ---
**Author:** ![MacLir](https://avatars.discourse-cdn.com/v4/letter/m/9e8a1a/32.png) [@MacLir](https://boards.straightdope.com/u/MacLir)\ **Post date:** [August 29, 2016, 2:06pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/30 "2016-08-29T14:06:43Z")
> [@Omar\_Little](#): > > Jesus and Peter walked on water, well the latter only till he got scared. I’ve heard a (humorous?) theory that this is how he came to be called Peter (Well Cephas, actually - means the same thing). His name was Simon, and Peter was a nickname. Peter / Cephas means “Rock” :smack: ---
**Author:** ![Galeiam](https://avatars.discourse-cdn.com/v4/letter/g/6de8d8/32.png) [@Galeiam](https://boards.straightdope.com/u/Galeiam)\ **Post date:** [August 29, 2016, 7:18pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/31 "2016-08-29T19:18:00Z")
The Basilisk lizard isn’t running on water. It’s just swimming really damn fast while using a method and calculations that wont mean a thing for a humans physiology. The Key to actual running on water is steps per minute, where steps replace rotations. Roll anything fast enough and it’ll travel across water fairly easily. The problem then becomes a matter of consistent force against water tension, motion, and oscillation. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 29, 2016, 8:46pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/32 "2016-08-29T20:46:53Z")
> [@Galeiam](#): > > The Basilisk lizard isn’t running on water. > > It’s just swimming really damn fast while using a method and calculations that wont mean a thing for a humans physiology. I get what you’re saying, but functionally, there isn’t any difference between ‘running on water’ and ‘swimming fast enough that only your feet touch the water’. > [@](#): > > Roll anything fast enough and it’ll travel across water fairly easily. The problem then becomes a matter of consistent force against water tension, motion, and oscillation. Nitpick: surface tension is a tiny, insignificant factor in any of this. The mass of water makes it something that forces can act upon. Viscosity also plays a part. ---
**Author:** ![Galeiam](https://avatars.discourse-cdn.com/v4/letter/g/6de8d8/32.png) [@Galeiam](https://boards.straightdope.com/u/Galeiam)\ **Post date:** [August 30, 2016, 1:08am UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/33 "2016-08-30T01:08:09Z")
> [@Mangetout](#): > > I get what you’re saying, but functionally, there isn’t any difference between ‘running on water’ and ‘swimming fast enough that only your feet touch the water’. Eh, best analogy is one used earlier. One is Dolphin tail skimming, the other is The Flash. Which actually ties into this bit. > [@Mangetout](#): > > Nitpick: surface tension is a tiny, insignificant factor in any of this. The mass of water makes it something that forces can act upon. Viscosity also plays a part. I actually had written out a larger segment to explain why I added surface tension to the reasons buy deleted in favor of simplification. In this instance viscosity would be attributed by surface tension and friction. As the high speed staccato would in effect create platforms in the water on which to move on. We don’t really need to explain why it would work for the OP to be satisfied, just how fast they’d need to be striking the water in order to achieve that result. A calculation which I in no way, shape, nor form can start on. ---
**Author:** ![Galeiam](https://avatars.discourse-cdn.com/v4/letter/g/6de8d8/32.png) [@Galeiam](https://boards.straightdope.com/u/Galeiam)\ **Post date:** [August 30, 2016, 1:14am UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/34 "2016-08-30T01:14:33Z")
Note that the reason running speed would not necessarily matter is because it is more a matter of contact amount due to surface tension than anything. A person could be running 80mph and still sink if it took them too long to transition their steps. ---
**Author:** ![countrarian](https://avatars.discourse-cdn.com/v4/letter/c/6bbea6/32.png) [@countrarian](https://boards.straightdope.com/u/countrarian)\ **Post date:** [September 6, 2016, 2:18pm UTC](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585/35 "2016-09-06T14:18:41Z")
> [@engineer\_comp\_geek](#): > > More info in the complete article here: > [Liquid Mountaneering Water Runner Video Debunked - Why You Can't Run on Water Video](http://www.popularmechanics.com/culture/a5829/water-runner-physics-debunked/) The popular science article includes the following quote: “It means each shoe should be a mile long and a mile wide.” That seems a rather dubious assertion. Even shoes have some displacement so a much lesser size would be needed. Any idea what they were trying to convey? [Previous page](https://boards.straightdope.com/t/if-humans-ran-fast-enough-could-we-run-across-water/763585.md?page=1)