There is no speed limit in that area that I know of. The vast majority of Palm Beach Island is private beaches in front of mansions. There is almost never anybody on those beaches. The exception is the odd hotel, private club & occasional public access beach. All three are very much the exception, rather than the rule in that area. Palm Beach Island beaches have been 90+% uninhabited anytime that I have been there & I'm there a lot. 98% uninhabited is not unusual.I don’t know how fast the boat was going, or what the speed limit is in that area. The reports cited have the divers 100 yds off shore, and I assume he was parallel to the shore since there are no inlets there. I also had no idea the skipper of the boat knew it was a popular snorkeling area.
Bob
Boats going south often run near the beach to stay out of the prevailing north currents & heavier seas that are typical further out. Yellow fins carry little weight & do not cut a chop particularly well. 100 yards out is closer than normal. Usually the chop is building again by the time you are that close.