From Wiki:
"It has been noted in media such as the Wall Street Journal that some groups such as African American and other minorities in the US are underrepresented among swimmers, particularly competitive swimmers. Some research in the 1960s, since discredited as spurious and unscientific, described blacks as recently as being inherently less buoyant and disadvantaged in water, and coaches have lost their jobs over statements in support of such theories. Nonetheless, statistically, black children between 10 and 14 drown at 4.5 times the rate of white children,[citation needed] most likely as a result of inadequate aquatic resources in some communities, less awareness, less swim accessory marketing in some communities and a dearth of black competitive swimmers, especially at the national level. Cost factors associated with competitive swimming also serve to discourage minority participation in the sport, as predominantly minority communities tend to be poorer and cannot afford it. This also explains higher drowning rates of black children. In light of this, a swimming requirement at some Ivy League colleges has been criticized as unfair to minorities."