Rare fossils of early whales arms show they may have swam doggy paddle style. It may not have been elegant, but they still managed to spread across vast oceans
Source:
https://www.newscientist.com/article/2216397-early-whales-swam-doggy-paddle-across-the-ocean-from-india-to-africa/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home