I'd have to agree with the whole black people in the water thing. I have several black friends, and even they admit that the majority of their race don't/can't swim very well. I mean look at skiing, snowboarding, hockey, swimming, diving, or anything related to water and the cold and you will see that black people simply don't dominate in those areas. That's the truth. Nothing racist, nothing hateful.
On the flip side, black people just tear up anything related to running, weight lifting, boxing, football, basketball, baseball, (athletics) etc. That's just reality.
Each race excels in different areas and isn't so good in others. Why can't that be accepted? Those politically-correct people out there really need to lighten up a bit. Don't interpret everything even slightly related to skin color as blatant bigotry. Just accept how God made you and live with it.
Edit - I believe the swimming thing has to do with black people have greater bone densities, and lower body fat percentages then other races. While this is not good for swimming, it is an advantage in land sports where muscle and power dominate. It seems to me that most black people are naturally muscularly defined, and that would most likely appear to be the reason.