The Las Olas Casino Pool was, in the International Swimming Hall of Fame’s own words, the first Olympic sized swimming pool in the State of Florida. It was designed by architect Francis Abreu and built by contractor John Obegon, measured sixty by a hundred and sixty five feet, and held four hundred and twenty thousand gallons of filtered salt water. Cost is reported two ways, a hundred and eighteen thousand dollars in one 1930 account and a hundred and twenty five thousand in a 1928 newspaper announcement. Roughly thirty five thousand people turned out for the opening ceremonies and swim meet.
The Collegiate Aquatic Forum started in 1935, an annual Christmas time college swim meet there. The Florida Historical Society’s history of the subject puts the origin of modern spring break right there, in the mid 1930s, when college swim teams came south to train in the new pool and spent the time between sessions on the beach. Through the 1950s it was still called spring vacation and drew about twenty thousand students a year. 
Then came the novel and the picture. Glendon Swarthout researched the book by taking his Michigan State English honours students to Fort Lauderdale for two weeks of what his own archive puts in quotation marks as research. His site records that national media, having overlooked the annual pilgrimage for twenty five years, sent reporters the following spring. Numbers jumped past fifty thousand almost immediately, and by the mid 1980s the city was drawing an estimated quarter of a million students a year. In 1985 the city’s mayor went on national television and said they were no longer welcome.