We have an indoor pool at home and I won’t get in unless it’s at least 28 degrees. A bit of a waste of time for me as I mostly float around on a Liverpool FC lilo which I got on a holiday in Greece a few years ago. My Mrs uses the pool a lot more than I do. She wears a harness with an elastic chord and just swims in the same direction for around an hour at a time until she gets bored. No idea what sort of distance she covers.