My head cannon for Serkis' character in Andor is that someone jumped out with him and towed him to shore. That or him and the other non-swimmers stayed behind and completely took over the factory. Otherwise it's just too sad.
@ArcaneRoboBrain It plays perfectly into the themes of the show (and Rogue One in turn) in some ways, though - you sacrifice everything for something you'll never see.
@redwizardrian Definitely ties in with the finale of that same episode. "What did I sacrifice? EVERYTHING!"
@ArcaneRoboBrain Oh man, just thinking of that speech brings back the chills. Stellan killed it as Luthen.