Sea Organ in Zadar, Croatia

The Sea organ is an architectural object located in Zadar, Croatia and an experimental musical instrument which plays music by way of sea waves and tubes located underneath a set of large marble steps. It is actually a water organ. The waves create somewhat random but harmonic sounds. The device was made by the architect Nikola Basic as

part of the project to redesign the old city coast (riva), and the site was opened to the public on April 15, 2005.

Here are a couple of videos with the sound of Adriatic sea playing.

[Source] Alexander Zakharov