ELI5: Does Pool Depth Actually Make Swimmers Faster? The Science!
Content Idea: The question "How much does the depth of a pool affect a competitive swimmer?" and "Is there an ideal depth?" is niche but really interesting. A simple explanation of the physics involved—like how waves bounce off the pool bottom, how swimmers create turbulence, and how deeper water helps these waves fade away without bothering the swimmers—can be super fascinating. Add in how pool design, like depth, lane lines, and gutter systems, impacts performance, and you've got content that can captivate a wide audience. This is especially true during big swimming events like the Olympics. It's the kind of "did you know" content that often does well, explaining why "fast pools" are designed the way they are.
Target Audience:
- Sports fans (especially those into swimming and the Olympics)
- Physics enthusiasts and students
- Curious learners (general ELI5 crowd)
- Aspiring competitive swimmers and their parents
- People interested in engineering and design, especially for sports facilities
Origin Reddit Post
r/explainlikeimfive
ELI5 How much of a difference does the depth of a pool effect a competitive swimmer? Also, is there an "ideal" depth of a pool?
Posted by u/floppysausage16•06/01/2025
I just saw that the Olympic trials for swimming is going back to Indianapolis where they set up the temporary pools last year. I assume that the pools used were as shallow as possible in orde
Top Comments
u/HurricaneAlpha
I need to see a sci-show YouTube video of this to understand it.
u/fiendishrabbit
World aquatics recommends a depth of 3 meters and the minimum for a 50m pool is 2.5m. This reduces water turbulence when swimming.
u/HurricaneAlpha
I need to see a sci-show YouTube video of this to understand it.
u/HurricaneAlpha
Honestly it's so slick I didn't even notice it. Splashless, even.
u/cubonelvl69
For an ELI5 answer, if you want to swim, you need to push water away from you. If you push water down in a shallow pool, the water bounces off the floor and comes back to you, which makes it
u/StupidSexyGiroud_
Did you ever win four races in a single day?
u/capt_pantsless
I'm upvoting you for the pun alone.
u/GalFisk
They handwave the finer details, but still float some pretty solid arguments.
u/CrispyChickenSkin
High school all American (honorable mention) swimmer here. Hold your applause. Please , sit down, it's too much.
Deep cold pools are faster than shallow hot pools. I'm not a scientist but a
u/DevelopedDevelopment
I think it's a mixture of water being "denser" when its cold, and I think something with the pool floor must mess with the water dynamics of swimming to slow you down.
u/geologyken27
Thank you for your service, sir. It’s been an honor to read the comment of a true American hero 🫡
u/FreestyleRobinson
The ideal pool depth for swimming is roughly 9 to 10ft. This water is deep enough that turbulence and reflecting waves do not significantly impact swimmers, but also not so deep that it has a
u/Jusfiq
> the ideal “fair” pool is one with near infinite depth and width.
Would the ideal pool then just rope off a rectangle with lanes in the middle of the ocean? In the Navy, it is called ‘sw
u/TehSillyKitteh
Boooooo
u/fiendishrabbit
World aquatics recommends a depth of 3 meters and the minimum for a 50m pool is 2.5m. This reduces water turbulence when swimming.
u/CrispyChickenSkin
High school all American (honorable mention) swimmer here. Hold your applause. Please , sit down, it's too much.
Deep cold pools are faster than shallow hot pools. I'm not a scientist but a
u/DarkKryo
That pun was perfectly executed, well done
u/HurricaneAlpha
Honestly it's so slick I didn't even notice it. Splashless, even.
u/TheMooseIsBlue
He kinda overstated that, because the larger the body of water the more affected by wind and tides. The ocean is generally moving a LOT and lane lines aren’t enough to do much about it.
But
u/flyingcircusdog
Yes, the Paris pool was only 2.15m deep, while the standard depth is 2.5m or more.
u/carson63000
Am I remembering correctly that the last Olympics, there was a bit of fuss about the pool being slow? I assume it was shallower than people hope for at the Olympics?
u/capt_pantsless
I suppose it wouldn’t hurt to get my feet wet with the physics.
u/capt_pantsless
I'm upvoting you for the pun alone.
u/cnhn
the ideal “fair” pool is one with near infinite depth and width.
okay not really, but really really big.
when a group of swimmers jump in and start swimming, they are making waves. th
u/zoinkability
Shallow pools are slower, deeper pools are faster.
[Here's an article that goes into more depth](https://www.triathlete.com/training/why-are-some-pools-faster-than-others/), as it were.
u/zoinkability
Shallow pools are slower, deeper pools are faster.
[Here's an article that goes into more depth](https://www.triathlete.com/training/why-are-some-pools-faster-than-others/), as it were.
u/cnhn
the ideal “fair” pool is one with near infinite depth and width.
okay not really, but really really big.
when a group of swimmers jump in and start swimming, they are making waves. th
u/fang_xianfu
Reminds me of when Mythbusters got Michael Phelps to swim through literal syrup (very dilute but still much thicker than water), and he almost couldn't do it because it was so weird and not w
u/mcpumpington
Take your hat off son, that's an all American
u/flyingcircusdog
Deeper pools reduce reduce the turbulence from swimmers, which is faster. So olympic pools will try to be as deep as they can practically build.
u/TheMooseIsBlue
Couldn’t they just do that with a cylindrical tank? Or a rectangular one?
u/ACorania
Waves don't just travel on top of water, even swimming right next to the wall means more turbulence coming back at you.
u/geologyken27
Thank you for your service, sir. It’s been an honor to read the comment of a true American hero 🫡
u/Whaty0urname
It was Nathan Adrian but your point stands.
u/ZwombleZ
You should dive into that article. It's deep.
u/flyingcircusdog
Deeper pools reduce reduce the turbulence from swimmers, which is faster. So olympic pools will try to be as deep as they can practically build.
u/linkinparkervii
That's because a cold pool makes you swim faster to get out of the cold water faster. If the water is warm, youre relaxed and don't mind just lounging around in it
u/Far_Dragonfruit_1829
Build the pool in a loop shape. Duh.
Actually, this was do e for an aquarium somewhere. The tank is a pair of cylindrical walls, one larger than the other, so the fish can swim continuously
u/DevelopedDevelopment
I think it's a mixture of water being "denser" when its cold, and I think something with the pool floor must mess with the water dynamics of swimming to slow you down.