Segregation deserves a lot of the blame for them:
[D]uring those decades when African Americans were kept out of New Orleans pools and beaches, black kids found other places to dive, like the other dredged-out canals around the city and dangerous parts of the Mississippi River. These unauthorized swimming areas would end up stewing a steady news feed of drownings. By the 1940s, the NAACP estimated that 15 black children had been drowning each summer in the city.
This chapter of New Orleans history helps explain some of the truths underlying the stereotype that black people don’t swim — but also illustrates why that reputation is ill-deserved, just like the notion that people of color don’t like the outdoors. The truth in it comes courtesy of the oft-cited statistics that close to 70 percent of black children can’t swim (compared to 42 percent of white kids) and black children are three times more likely to drown than white kids. But clearly, those stats don’t tell the whole story.