The Morske Orgulje (Sea Organ)

Two art installations in Zadar, Croatia are featured in the video above.  The "Sea Organ" uses the power of ocean waves to generate sounds from organ pipes embedded in a shoreline structure, as explained at OddMusic:

Each musical organ pipe is blown by a column of air, pushed in turn by a column of wave-moved water, through a plastic tube immersed into the water. The pipes' musically tuned sounds emanate to the surroundings through apertures in the vertical planes of the uppermost stairs. The 7 successive groups of musical tubes are alternately tuned to two musically cognate chords of the diatonic major scale. The outcome of played tones and/or chords is a function of random time and space distribution of the wave energy to particular organ pipes.

In this part of Croatia the prevailing musical tradition is the spontaneous four-voice male singing, with melodies and chords conforming to the diatonic major scale. The 5 musically tuned pipes of each section are arranged in 1.5 meter spacings. A listener, standing or sitting on a chosen point on the scalinade, should be able to hear 5 to 7 musically tuned pipes play their natural music. Thus, whole five-pipe sections are tuned to one musical chord. The citizens of Zadar are extremely proud of the first natural musical organ driven by the sea waves ever to be constructed...

The nearby solar-powered light installation is explained at Physics Buzz (whence the video).