Location: Valley of Eternal Spring
Objective: Follow Tethys and Oceanos’s children into the depths
We acquired this quest by heading into a cave next to a waterfall containing a chest in the southern part of Valley of Eternal Spring.
The cave is directly south of the Hall of the Gods fast travel point near the shore. After the dialog, exit the cave and follow the statues of sea life to the ocean.
There you will discover an underwater altar. Interact with the underwater pedestal then head back to shore towards the cave to find a giant clam with a Hera statue in it. Interact with the statue to complete the quest.