Another thing is if you didn't know the water temperature you might not want to risk it not knowing how cold it was. Now, if I had been in that situation and knew the water was 59 degrees I probably would have gone for it (assuming I was traveling by myself) unless the current looked strong or there was no safe way to get to the water without risking serious injury...I swim in low 60s water (no wetsuit) pretty regularly in the summer, up to a mile or more (parallel to the beach, not very far out) so I would be pretty confident of my ability to make a 100 yard swim in those conditions. Not knowing the water temp would be different.