I haven't been able to locate high-quality film of his races, and underwater filming wasn't done, but this clip from Tarzan shows Johnny Weismuller's powerful "American Crawl". The clip repeats, and has been slowed to reveal more details. The original movie used a speeded up effect version.
--- I believe the movie title is "Tarzan Finds a Son!"
![](https://i.ytimg.com/vi/kM7pQZxtrLg/mqdefault.jpg)