This is a typical case in which the musical material appears to be minimal, and easy to manage, but once you actually play, many fine details are revealed. The song is built around a six-measure ostinato that repeats endlessly (a four-measure introduction is used to introduce and break the ostinato here and there, however; listen to the song to know where). So once you've learned six measures of piano, you're apparently done.
Things are not that easy, however: the left and right hand parts main accents are sometimes shifted by one eighth; moreover, Stipe never sings exactly the same melody; finally, the internal rhythm of the melody is often contradictory with the ostinato. Indeed, much the beauty of this song is in the contrast between the hypnotic ostinato and the endless variation of the melody. Personally I find particularly difficult to sing and play on the last two measures of the ostinato, where the 3+3+2 metric suggested by the bass notes is almost always in strident, marvelous opposition with the melody.
The piano part for Nightswimming poses no technical problem. My transcription (Lilypond sources) tries to be as close to the original as possible, so corrections are particularly welcome.
I usually play this song several times in a row—I just can't stop.