Only a few yards, maybe 20-30 yards if I am lucky, in sea-water. I cannot float so expend a lot of energy very rapidly just trying to stay on the surface!
I don't swim distance. I could crawl 1500 metres back in the day, now I only hit the water to cool off. Adelaide doesn't have waves worth riding, so I don't swim out to the breakers any more - there aren't any.