Most definitely this one.
While "going with the flow" seems to be the way to endure this kind of extremely massive phenomenon because going against it is a lost battle, the fact is that "the flow" is downwards, leading to an icy tomb with no air and no moving space. Plus, if you swim with it you might end up going faster and faster and, when it finally stops, that might not be fun (plus, swimming into a tree seems likely).