The ocean drum is a percussion instrument that can produce soothing sounds which sound just like the ocean.
Playing
The ocean drum is held by the frame, with the heads horizontal, and played by rolling the wrists so the drum gently tilts in all directions. The metal beads inside roll over the bottom head like water rolling over the shore. Different speeds produce different sounds. Stopping and starting suddenly creates crashing wave sounds.
References
Ocean drum Wikipedia(Text) CC BY-SA