Pan Zhanle achieved something pretty special during the men's 100m freestyle final on Wednesday night.
For one, he set the first and so far only world record of the Paris Olympic Games.
The 19-year-old smashed the previous mark 100m in 46.40 seconds, setting a new benchmark by 0.40 and winning gold by over a second from Australia's Kyle Chalmers.
With the greatest swimmers in the world all congregating for these Olympics, it might surprise some that just one world record has fallen at the Games so far.
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Indeed, six world records were set at Tokyo in 2021, eight at Rio in 2016 and nine at London 2012, the first Olympics after the chaos of the super suit era.
But there's a clear reason why it's been harder at this Games.
The pool is slow.
How on earth can a pool be "slow", I hear you ask?
It's a respectable question. It is 50 metres long, has 10 lanes and is filled with regular H2O.
So how can it possibly be any quicker or slower than any other?
Fathoms below
For a start, it's not very deep.
It might not be obvious from television, but Paris La Défense Arena is not usually a swimming pool.
In fact, they normally play rugby here.
Behind the TV cameras is the other half of a giant arena capable of sitting 30,681 people.
This pool is a drop-in model and, to ensure that front-row seating could still be used, they could only fit a pool that's 2.15 metres deep.
For reference, World Aquatics recommends a pool be 3 metres deep, and has set a new minimum limit of 2.5 metres.
Incidentally this shallow pool will also likely have an impact during the water polo matches that shift here in a handful of days when the swimming competition is over.
It would mean some of the taller players will be able to bounce off the bottom far easier than they would in a deeper pool, something they are not allowed to gain an advantage from or risk giving up a foul.
What's the difference?
So why does a shallower pool matter?
In short, as swimmers move through the water, they create turbulence.
That turbulence makes the pool rougher and not as easy to swim in.
The shallower water gets, the slower water moves on the surface.
This is the reason waves break onto the beach — they literally slow up as the water gets shallower.
That reduction in speed may have an impact on how swimmers "feel" the water and means that they cannot generate as much speed as they are used to.
Of course, some people think this is all a bunch of hokum.
"I've heard the rumblings, but at the end of the day we're here to race," American star Katie Ledecky told AP.
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"We're all fast swimmers. We make the pool as fast as we want it to be. I'm not really thinking about it."
If it's good enough for the GOAT of distance swimming, then surely it's good enough for everyone else?
Well, Ledecky is always in the middle lanes on account that she's faster than most other people.
At the edges, that chop gets a bit more difficult to handle.
"It's a tough pool to swim in, tough when you're on an outside lane," British swimmer Jacob Whittle told The Sun.
"It's just one of them pools, some pools feel great, some pools don't.
"A few waves, feels a bit strange being a bit shallower, nothing that we can't deal with.
"There's a lot of waves when coming out of the turn but it's nothing to a high extreme.
"It's just something mentally that you have to deal with."
Off the deep end
So, perhaps the talk of a slow pool is a self-fulfilling prophesy?
And does it even matter?
Not according to 100m freestyle silver medallist Kyle Chalmers.
"It doesn't matter whether I'm racing here in Paris or at a local country pool in South Australia," Chalmers told AP.
"It's all about winning that race in the pool.
"Everyone has the same opportunity. Everyone has a lane. We're all swimming in the same pool.
"It doesn't matter about times. It's about getting your hand on the wall first and winning the race.
"The times are never really all that remembered."
What will be remembered is the extraordinary atmosphere that has been produced in this magnificent arena and the medals that were won.
The records? They can wait.
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