[…] I would first agree with [Earl] Wasserman that the last line ["[shapes] Which walk upon the sea, and chaunt melodiously"] alludes to Jesus walking on water, the point of the allusion being the kerygmatic expression of a form of transcendence, which is more or less specified by the way the other hemistych of this remarkably balanced thirteener – "and chaunt melodiously" – recalls how it is on the breath of enamored air and song that all the vigorously launched members and voices of this scene are sustaining their courses.
Source: wiktionary