My experience has been the opposite of this. I'm taking my first swimming lesson next Monday, and its got me interested in asking people if they can swim. Almost all of the black people I've asked either cannot swim, or are not confident in their swimming abilities. One co-worker (black woman 30s) grew up with an in-ground swimming pool in her back yard, but said she didn't get in much because her friends/cousins couldn't swim. She says she can get from one end of the pool to the other, but isn't really a swimmer.
Another co-worker (black woman 40s) is going on vacation to Jamaica soon, and she was showing me the Chloe beach bag she bought. I asked her if she could swim. She said, "No. And I don't want to either. I'm just going to be cute sitting by the pool with my beach bag and sun hat". She said pools and bodies of water are dirty and she isn't getting in...
The former co-worker who grew up with a pool also mentioned something about cleanliness and her vagina, and not taking baths, only showers... When I was growing up I had the opportunity to learn to swim at the community pool, but I declined because I looked around at my hood peers and decided I didn't eat to be in the same "bath" as them. So, I'm starting to wonder if some of our (black women's) aversion to swimming has anything to do with our hyper cleanliness.