Low tide

The pool looks unattractive at ultra low tide. Who would want to paddle or swim off this patch of slimy mud?

If you look closely you can see a single black flip flop on the muddy bank. There's a joke that you never have to pack two, because wherever you go there is  always a flip flop.

Australia has a different name for flip flops. I haven't used it, for fear of offending English sensibilities.