In the Croatian seaside town of Zadar, concealed beneath a set of large white steps leading into the water, is the Zadar Sea Organ.

Similar to the Wave Organ in San Francisco, California, and the High Tide Organ in Blackpool, England, the instrument consists of a series of 35 tubes and a large resonating cavity, which is played by the wind and the sea. The organ’s music is eerily reminiscent of the melancholy sound of whale calls.

The Sea Organ was designed by architect Nikola Bašić and completed in 2005. Just behind it is another art installation he created — the Sun Salutation — which has an ethereal pattern of glass panels that capture sunlight to power their own light show that is a tribute to the solar system.