Description
This last portion of the chorus is where the band breaks down into a reggae feel. This is an interesting twist on a song hook; usually the music will be at its most pronounced when the vocalist is singing the main lyrical theme, but in this case the "message in a bottle" lyric is sung over a quiet section. Again, the listener is engaged by the shift to a quiet reggae feel, which then snaps back into the jazzy, stacked 5ths main riff in the verse.
Notice the interval movement of the chords: there's a C# minor moving down a major 3rd to an A major (a very typical movement you'll hear in lots of songs and styles), then back up a major 3rd to the C# minor. Then it moves down to an F# minor, a minor 3rd down from A. This chord is enharmonic to A major: both F# minor and A major contain the same notes. So overall, this progression moves back and forth in major 3rd's, then down a minor 3rd.
At the end of this whole phrase, there is a "harp harmonic" that is played, a dreamy sounding little nuance that tags the end of the chorus. This is the most difficult element of the song and might take some work to get down. For a full tutorial on how to play harp harmonics, go to:
http://www.guitartricks.com/tutorial.php?input=1046