Actually, it was 1.13 mph…
…and it was in a pool. 
I took my youngest daughter to her swim practice this afternoon and, since I was able, I went for a swim myself. (They practice in two lanes of a Durham Parks & Recreation pool… I swam in one of the other lanes.) It was weird… it was the first time I’ve swam any significant distance in a long time. I was feeling seriously fatigued within the first 300 yards, but I kept going, though not very quickly. I also had a brand-new pair of goggles which were defective (by design… they punched a hole in the eye-seal for the strap-loop… morons) and leaked steadily the whole time. I might have swam farther if I hadn’t had to stop to empty the one eye-cup every 25 yards.
I managed to finish 2000 yards (a mile is 1760 yards) in the hour of Amanda’s practice. My goal was the mile, but once there and seeing I had five minutes left, I figured I might as well go for the nice, round 2000 yards. Embarrassingly, the extra 200 yards took the entire five minutes. :/