Talk to the mileltih, Kun, in Liyue Harbor behind the left teleport waypoint, and you will be asked to clean up the remains of the destroyed Jade Chamber.
The first location you'll have to clean up is very close. Head to the location and pick up the 5 boxes in the water.
Next location is on the other side of town. Similar to the one before, simply pick up the 5 boxes in the water.
After picking up all 5 of the boxes, you will get the "Water-Logged Box", a key item to progress with the quest. Talk to Kun back at the pier, and he will tell you to go someone who knows better.
Talk to Baiwen in Yuehai Pavilion to complete the quest and get the rewards.
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