Written during the Out of Time recording sessions, but not completed until later, Nightswimming was, for a long time, a simple, circular piano pattern that Mike Mills established gradually. Holding the track back from Out of Time meant that it benefitted from the more confident and complete string arrangements that John Paul Jones added to Automatic For The People.

Uncommonly among R.E.M. songs, Nightswimming is autobiographical, looking back on carefree summer nights of old, when the gang would go skinny-dipping in the local lake.