How to do the fin task of bathing the deep sea in the original moon?

1, first came to the shrine behind the Coral Palace.

2, dialogue with witches triggers tasks, and there will be four places. This strategy is fin.

There will be two disks when you arrive at the mission site.

4. First turn everything on the left to the middle and have a look. When you go to the right, you will find that you have two, and then you can directly align the other two. Thirty original stones will be awarded to the fin of the sea after the mission.