Oceans are capable of being crossed by little more than someone clinging to or sitting on a log (not with a particularly high survival rate, mind). Or bundles of papyrus reeds or balsawood rafts, as Thor Heyerdahl demonstrated. I personally know several people who've rowed across oceans. Some of them multiple times and/or multiple oceans.

The odds of rowing to Ceres or Alpha Centauri, let alone the Andromeda Galaxy, on a log raft, are rather slim.