The music rock puzzle is one of many puzzles that you'll find in the limited-time archipelago region in Genshin Impact. There's not much direction given for this puzzle, so it can be confusing. Here's a step-by-step walkthrough for how to solve it and claim the three chests as your reward.
Genshin Impact introduced the Golden Apple Archipelago region as part of its patch 1.6 update. The region will be available for the duration of 1.6 only, so players should take the opportunity to fully explore the region and open all its chests before the patch ends. Note that to gain access to the music rock puzzle, you'll need to have completed the "Summer Vacation: Proceed With Caution" event quest, which unlocks Act II of the event.
Genshin Impact Music Rock Puzzle Guide
As you venture through the Golden Apple Archipelago, stop at the location below on the Broken Isle. You'll see a curious arrangement of five pillars, and five stones in the ground. When you step on one of the stones, it may make a musical tone.
Each stone is connected to a pond atop the large hill it is facing. There are five hills, corresponding to the five stones. To complete this puzzle, you'll need to travel to the top of each hill and adjust the water level of each pond. Once the water level is correct, the corresponding stone in the ground will make a musical tone when you step on it.
To figure out what the water level of each pond should be, you'll need to venture into a cave beneath the hill at the center (with the teleport waypoint). There, you'll find a mural displaying this image:
The mural tells you the water levels that each pond should be adjusted to: low for the center and east ponds, medium for the west and southeast ponds, and high for the southwest pond.
Travel to the top of each hill and find the pond. There will be two stones next to the pond; stepping on the left stone lowers the water level of the pond, while stepping on the right stone raises the water level. Some ponds may start out empty, and you'll need to break a hydro amber or a rock pile to direct water into the pond.
Once you've adjusted each pond correctly, return to the five stones and pillars. The marks inscribed on each pillar indicate the order in which you should step on the stones. The order is: center > bottom left > top right > top left > bottom right.
Upon stepping on all five of the stones in the correct order, you'll hear a tune and see a brief cutscene. Then you can claim your reward - two precious chests and a luxurious chest. You'll get a total of 30 primogems, along with other items.
Genshin Impact's 1.6 patch brought plenty of new content as well as a whole new region to explore. Don't miss out on collecting echoing conches for a free Barbara skin, or trying your luck on the Klee rerun!