# Is it possible to have a waterfall big/slow enough for a human to swim up it? **URL:** \ **Category:** Factual Questions\ **Created:** [April 12, 2011, 8:25am UTC](https://boards.straightdope.com/t/is-it-possible-to-have-a-waterfall-big-slow-enough-for-a-human-to-swim-up-it/578064 "2011-04-12T08:25:34Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [April 12, 2011, 8:25am UTC](https://boards.straightdope.com/t/is-it-possible-to-have-a-waterfall-big-slow-enough-for-a-human-to-swim-up-it/578064/1 "2011-04-12T08:25:34Z")
It’s 2012 and Michael Phelps, uh, marries Donald Trump in a surprise wedding. Yeah. With his new-found wealth, Phelps decides to build himself a lair that only _he_ can access… by swimming up the _waterfall of doooooooom_. Is that even physically possible? Does the waterfall need a certain volume of water or a certain maximum flow rate? Does gravity’s effect on water on this planet make it totally impossible? Or, let’s say I have a huge blimp filled with water. Could I shoot it with a slingshot, start a small leak and then shoot a torpedo up the stream? ---
**Author:** ![Horatio\_Hellpop](https://avatars.discourse-cdn.com/v4/letter/h/e5b9ba/32.png) [@Horatio\_Hellpop](https://boards.straightdope.com/u/Horatio_Hellpop)\ **Post date:** [April 12, 2011, 9:56am UTC](https://boards.straightdope.com/t/is-it-possible-to-have-a-waterfall-big-slow-enough-for-a-human-to-swim-up-it/578064/2 "2011-04-12T09:56:47Z")
Swimming involves pulling yourself through water that’s either inert or going the same way you are. You can try swimming upstream, but even something as slight as a riptide can kill you. So, no. A waterfall is out of the question for any human. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [April 12, 2011, 10:15am UTC](https://boards.straightdope.com/t/is-it-possible-to-have-a-waterfall-big-slow-enough-for-a-human-to-swim-up-it/578064/3 "2011-04-12T10:15:40Z")
If the water is actually falling, as in vertical, then it will fall far too fast to swim up. If it is not falling but flowing down a steep slope then it just depends on your definition of “waterfall”. How shallow can the angle be before it is not a waterfall? Any river is a “waterfall” flowing downhill at a very, very shallow angle and course you can swim up a river. So I suppose the answer is no, unless you are using a definition of waterfall far broader than in common parlance. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [April 12, 2011, 11:55am UTC](https://boards.straightdope.com/t/is-it-possible-to-have-a-waterfall-big-slow-enough-for-a-human-to-swim-up-it/578064/4 "2011-04-12T11:55:28Z")
According to [this,](http://wiki.answers.com/Q/How_fast_does_Michael_Phelps_swim_in_miles_per_hour) Phelps can swim at about 4.7 MPH. Running through the equations for freefall, I find that a waterfall with a height of just 0.74 feet results in water (at the bottom of the fall) traveling at 4.7 MPH. So the tallest honest-to-god freefall waterfall that Phelps could ascend is less than a foot. ---
**Author:** ![Autolycus](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@Autolycus](https://boards.straightdope.com/u/Autolycus)\ **Post date:** [April 12, 2011, 12:15pm UTC](https://boards.straightdope.com/t/is-it-possible-to-have-a-waterfall-big-slow-enough-for-a-human-to-swim-up-it/578064/5 "2011-04-12T12:15:18Z")
Well, it’s got a DC of 80, so it’s impossible for non-epic humans. ---
**Author:** ![Alka\_Seltzer](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alka\_Seltzer](https://boards.straightdope.com/u/Alka_Seltzer)\ **Post date:** [April 12, 2011, 3:02pm UTC](https://boards.straightdope.com/t/is-it-possible-to-have-a-waterfall-big-slow-enough-for-a-human-to-swim-up-it/578064/6 "2011-04-12T15:02:08Z")
On Earth, no. But it might be possible for a human to swim up a waterfall on a very small planet with low gravity. Good luck finding one of those that also has liquid water.