How The Other Half Bathes-1915
The same group of people seated in the foreground can also be seen here, posing amid the souvenirs at Gus' Baths. The adults are dressed in the same outfits while the two younger people have switched to bathing suits. Note that, for the young girl, proper swimming attire included a bulky cap and a heavy wool bathing dress. She's actually wearing MORE clothes than in the earlier picture!
At least four of the men in the photo are wearing identical suits so they are likely rentals (from Gus' Baths.)
The members of this party were staying at the Palm Beach Hotel which might explain why they weren't enjoying the facilities that Flagler's Breakers hotel provided a mile or so to the north.