There are a lot of big gators like that at Kiawah Island. Used to be a lot more, before it became developed into a resort. I would see them swimming in the surf and sunning on the beach in the Spring. They still roam around at night, looking for pets to eat, so if you are golfing there or Hilton Head, don't go walking down a road or trail in the swamp at night, as they lie in ambush for unwary animals.
When they used to come surfing in to take a sunbath, it would clear off the humans! Actually, to see the sight of them on a warm Spring day, glistening in the surf, used to excite me, long ago. Of course, I was 100 yards back, up on the sand.
But if the swimmers could see some of the big bull sharks, makos, great whites and hammerheads just offshore, a lot fewer of them would go into deep water. Alligators are really rather shy, until they get over ten feet and start to feel like the 800 pound gorilla... er..gator. What really spins them up is the sight of a dog; they love to eat dogs and will really come after them.