I’m not sure what phenomenon you’re describing here - how was the surface coloured?
as a native Aussie who lived in UK for 3 years, I never saw a blue ocean there… it was always dirty grey… so the claim may well be true 
The floor and walls of the pool are usually blue or green.
Ah, thanks - I thought you meant the surface of the water (and was wondering how you could ever paint it).
Freeze it?
Best close the diving board if you’re going to do that.
Oil based paint floating on the water 
Again, close the diving board, you don’t want green people walking around your pool
But it’s St. Patrick’s Day.
Thats for sure. Yellow (ahem) and blue make green
I went swimming in a public pool once where the water was suddenly deep, murky green one day (we’d been going there nearly every day and it was fine, then it was this impenetrable cloudy green colour). They still let us swim, but for some reason, we never thought to ask why it was like that (or we did, and they didn’t know/tell us - I can’t remember).
I think it might be that they filmed something there and had dyed the water to make it look like the sea or a lake (obviously would only work in a cropped shot, with the right lighting etc).
Note that “clearness” (clarity?) has nothing to do with color, at least when describing liquids. Not so important normally, but keep it in mind before turning in a lab report :). A clear colorless solution and a clear dark red solution are both clear.
Back in my old Thermo lab days, I saw liquid H, He, N and O. Of these only Oxygen had a noticable color. A beautiful pale blue. In the 1-2 cups range the rest were as colorless as a comparable amount of water. I have no idea what a swimming pool of Hydrogen would look like.
Could that be due to trace amounts of ozone in the oxygen? IIRC liquid ozone has a rather strong color.
No they aren’t. Every public/recreational olympic style swimming pool I’ve ever seen (and I’ve seen hundreds) was finished in white. Sometimes it’s white tile, sometimes it’s a thin layer of plaster over the gunite or concrete.
AFAIK liquid oxygen is slightly blue. It’s just its natural colour, I don’t believe it’s due to the presence of ozone. Liquid ozone, as you point out, is deep blue.
I think you two are using different life experiences. IME many big/public pools ARE white. OTOH most small private pools ARE NOT white IME.
Regardless, the water an indoor Olympic style white bottomed pool still looks blue. So it’s clearly (ha!) not the bottom of the pool or the reflected sky producing that color.
Yes, but here is the way I remember it.
You take a bunch of liquid oxygen. You let most of it boil off. What’s left is small amount of deep blue liquid ozone, because ozone boils off at a higher temp.
So, it appears in general that run of the mill liquid O2 contains a good fraction of ozone. So is true pure O2 slightly blue, or is it the diluted ozone giving it the blue tint?
Just going from memory and pseudo logic here.
So water must have a blue tint then. That’s something I didn’t know after 48 years of life.
I guess you don’t get out of the house much?