How common are seawater swimming pools in Australia?

[Harry Potterish]

Hello all,

Now someone told me about their swimming pool somewhere coast in North Australia, it gets its water when tide come in, and that water leaves again when the tide goes out, keeping the water in the pool always fresh, no chemical treatment required.

Can anyone have an idea about this topic please help?

Thank you so much
Harry Potterish

[PinkertonD]

This has been asked before, I am too lazy to search but I suspect it was you who asked it.