Technically, I'm a competent swimmer. However I've never had any stamina in the pool (used to just sink - swimming when you have negative buoyancy is really hard).
My daughter has just taken up swimming again (for her DoE). Not swam apart from splashing about for 3 years or more.
Last week she got back in the pool and did 64 lengths, 1600m, in an hour.
This week it was 74 lengths - and she complained she felt slow, but was taking it easy.
I have no idea where the child gets it from, her mum doesn't have stamina either.
What's a reasonable distance to swim in an hour, for a regular swimmer?