Sorry you had that experience surprisetalk. Glad for you that it was all ok.

Theres a saying that comes to my mind, I think it used to be a lot more common.

"it only takes 6 inches of water to drown"

Fall funny, get nocked out and land in a puddle or whatever, or cant lift your head out of it for whatever reason etc etc.

I am VERY conscious of water & my kids, being a scuba diver myself I have a fair respect for the sea as well, and still we have had experiences that left us a little shook.

Scary. Glad it turned out okay. The rule should be any standing water feature below 3' (1m) above grade should be enclosed by a fence to a height of 4' (1.3m) above grade if kids are anticipated to occupy the space.

And, for oceans, rivers, and flood water: remember that 1m³ of water weighs 1.1 ton/1 tonne.

Also dangerous: low head dams. https://practical.engineering/blog/2019/3/16/drowning-machin...

Finally, don't sleep in or build homes in flash flood areas: (US): https://msc.fema.gov/portal/home

Related PSA that drowning doesn't look like drowning [0] — people don't yell, splash, and wave like you might expect and is "almost always a deceptively quiet event".

[0] https://slate.com/technology/2013/06/rescuing-drowning-child...

On a related note. Don't assume if your child slips/falls into a pool, you will hear it. I happened to see my daughter step off a ledge in a hot tub once and she just vanished. Not a sound. If I had been facing the other direction, I would have had no idea.