Yeah, someone else wrote about 57F. That’s VERY cold, as the effect of water on body temp is dramatically different than air. It’s a good thing it wasn’t very far for the ones who jumped/swam.
That's cold, but not like freezing water. We used to body surf in water that cold without wetsuits and it would take about half an hour before the shivering set in. We'd come out and sun ourselves for a half hour and then head back in. Needless to say you work up quite an appetite doing that. An elderly person would be in trouble, though.