Thanks for the xplanation Hbeao. And I played trumpet and baritone in band and yet still didn't know that term. I should have paid attention more I guess.
An arpeggio is the notes of a chord played in succession, either ascending or descending. An example (for a G major chord) would be playing the notes G B and D one after another, as they are the notes of the tonic triad of G.
Nice peaceful intro. Cool effects coming in. Well named as it has an underwater sort of sound plus the poeticalness of it is something I can appreciate.