Pink floyd - Echoes > the Crystal Voyager footage - 1973 The closing sequence, Greenough's short film Echoes, is generally considered to be the highlight of the film. Filmed with a camera in a waterproof housing strapped to Greenoughís back, the sequence is composed entirely of slow-motion footage shot inside the curl of waves, edited to the 23-minute song "Echoes" by Pink Floyd. The group reportedly allowed Elfick and Greenough to use the music in their film in exchange for the use of Greenough's footage as a visual background when they performed "Echoes" in concert.