4yo unattended in pool

[Anon01010]

My ex recently started taking our 4yo old swimming. 4yo has had two lessons I believe and had no prior experience in pools so is still learning. They do an open swim session after. 4yo has just informed me his father showed him how he can swim the whole length of the pool under water, leaving 4yo unsupervised in the pool. Am I right to be worried/annoyed by this or should I just let it go?

We’d practice swimming then I’d do a couple of lengths whilst they played with pool toys near the steps at 4. There was a lifeguard, possibly mine we’re better swimmers at that age.
And what would have happened if the life guard had to attend to another swimmer who was in difficulty? Life guards are not their to provide supervision for children whose parents who want to do a few lengths on their own leaving. Our pool has very strict rules about that - brought in because that is what parents were doing.

How big is the pool?

the teaching pool near me is 5m by 5m.

also, how sure can you be your 4 year old is reliable? It’s quite likely dad did go underwater but many 4 year olds do exaggerate.

either way, if you are separated this isn’t something you have control over.

I don’t want to appear dismissive to those who have suggested my 4 year old’s version of events might not be reliable to go off of, but I really do trust what he says, he is not the type to exaggerate and this is exactly the type of thing his dad would do. I can’t ask his dad because he will deny it happened at all. I know the big unknown is how long he was actually left unsupervised for and I can see how that does make some difference. My wider worry is about the future and if his dad did something like this on holiday for example where there may not be any lifeguards for back up.