The Eye of Watatsumi is a subquest for the Moon-Bathed Deep quest in Genshin Impact. You need to find the Eye of Watasumi, then break the seal over the shrine.
Finding the Eye is simple, just open your quest list, then travel to the waypoint when you select the Eye of Watasumi quest under the Moon-Bathed Deep. The Shrine will be sealed, and you can read a tablet beside it on the left side that will point you toward investigating the north, south, and west of the island.
You will need to use your Elemental Sight to find three orbs of Electro energy in the areas shown on the map above. The one to the north and south can be found beside the sea, while the one to the west will be up on the small hill. Use the Elemental Sight to see a wispy trail of Electro energy that you can follow to each one.
When you are there, use a non-Electro ability to break the Orb, then defeat the enemies that spawn in. You don’t need to defeat the enemies if you are in a rush. You can simply move on to the next area instead. Once you have done this for all three Orbs, return to the shrine and you will be able to interact with it and finish the quest.