I was a kid growing up in Miami when this came out. Spent most of my free time at the beach back then. We saw one of the first showings of Jaws when it came out in '75, line around the building...
Next day, beaches were packed but VERY few people were getting into the water. When somebody got up and started walking toward the water, people were acting like meerkats, stopping to watch the guy walking towards the water, like... is he frikin crazy?!?