Soroban leads the way to the place where you will undertake the ritual to receive a blessing.
This quest is available if you have completed the quest Of Kojin and Kami, and have reached level 63.
Starting the Quest
Talk to Soroban in Tamamizu in the Ruby Sea to begin the quest.
Speak with Alisaie
Go down a slope and go to the quest icon on the map. Talk to Alisaie and there will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.
You can now dive underwater. By default, if you are swimming on the water's surface, you can dive (but not in shallow water) by pressing Ctrl+Spacebar on keyboard or by pressing B on Gamepad. This can be changed from the default by going to Main Menu > System > Keybind, under the Movement tab, where you can change the setting for Flight/Diving - Descend.
If you accidentally dismount, you can go back to Tamamizu and go to the ❕ to talk to Soroban and mount another striped ray.
Speak with Lyse
Go southwest and downward to where the orange arrow is pointing in the minimap. Ride the mount through the whirlpool, then dismount using the action that was added to your hotbar/crossbar, and talk to Lyse to complete the quest.
Completing this quest unlocks the use of underwater emotes. You can check which emotes can be used underwater by going to Main Menu > Social > Emotes and putting the cursor on an emote. The emote information at the bottom of the interface will have icons to show when the emote can or can't be used, such as while swimming or underwater.
Next Main Scenario Quest
After you complete the quest, talk to Lyse to accept the next quest: Forever and Ever Apart.