So, clearly the solution should be a figure-eight swimming pool? Where 1/3 of the time you're going straight, 1/3 overcorrecting left, 1/3 right

No, the solution is to move the water and have the swimming equivalent of a treadmill. NB: this already actually exists, only remember seeing it in a video at some point though.

You probably saw it in person as well, it's called a river :) In Zurich there's multiple places where you can swim in the Limmat, and it takes quite some effort to stay in place - one example is https://images.app.goo.gl/qTASdR51yDTiCk299 (of course you could go without the installation but this allows people to use it that would be afraid of getting carried away ...)

It would be so amazing to live near a river with water clean enough to do this :(

Is there something like this in Berlin?

Could be some settings at the new Wellenwerk that achieve this

The problem with this is that the current is constant. When doing a long set I sometimes accent the arms and the legs alternately over say 200m. Well typically three lengths of arms and one length of kick dominated effort. The thing is the speed does change from one technique to other but moving the water at a constant speed over a short distance doesn't work properly. So it's cute for a little swimming but it's not compelling for serious training. Never mind if you want try doing an individual medley set.

make it a bit longer and have it vary the speed on the position of the swimmer...

Or just have the water channel narrow so the water velocity increases as you move forward.

That's true. The motivation for the swimmer is to not get sucked into the intake. I can hear the coach laughing maniacally as he turns the speed up to 11.

It's called a river. I do a lot if river swimming, but you need to live in a country with clean rivers.

But swimming in lakes is more fun and better for your technique.

They have this at the main Google campus in MTV

"Endless Pool".

Interesting - do you know if the negative effects of circular swimming pool affect fish hatcheries? (fish are forced to swim against current)

If I had to guess, I'd say not as much b/c of the size of the fish.

Most fish farms force fish to swim through a current of running water. I think most are concrete “runs” that continuously pump water through. At least what I’ve seen in the US is that way. There are now many overseas fish farms.

How about a pool in a rotating orbital space station? Just keep swimming forwards and slightly uphill :) Just don't lose the fake G or you could be the first person to drown in space.

It’s never uphill though, while rotating “halo” looks like it bends upwards, force-wise it feels flat.

That was a plot point in the movie "Passengers".

I once saw a documentary about a fish farm where they had tanks where fish were forced to swim in circles. Probably not the most fish friendly environment.

Regular pool, open two lanes, swim laps (up one lane, down the other). It's done with two lanes, so there is enough room to pass. I've seen it done this way several places.

I’m confused as to what you are suggesting here? Normally you swim right side of the lane and turn going back on the “left side”, with room to pass on the inside unless the lane is filled with two many people. What does using two lanes add, except ruining your turns?

If the pool was long enough, that wouldn’t be an issue. Thanks for the excellent post.