If you like Dark Side of the Moon try Obscured by Clouds, It is the album released before DSotM and the track "Childshood's End" is what inspired the band to make DSotM (allegedly)
Also, Animals, Wish you Were Here and Meddle are as equally as good as Dark Side of the Moon. (If you listen to Meddle the last song Echoes has a 5-minute section in the middle which is sonar and whale noises)