Within the Depths of Erinnyes is the final Genshin Impact World Quest in The Wild Fairy of Erinnyes quest chain. It automatically unlocks after completing Wilting Weeping Willow and Furious Mouth of the Spring, and unlocks a secret path in Marcotte Station, leading to the depths of Erinnyes.
Completing Within the Depths of Erinnyes will permanently revive the Weeping Willow of the Lake. Read on for a full walkthrough of the World Quest, as well as combat and survivability tips during the cleansing section.
Within the Depths of Erinnyes quest walkthrough – Genshin Impact
The quest starts at Marcotte Station, where dialogue with Pahsiv will automatically trigger. Once done, interact with the three statues surrounding the fountain to offer the Teardrop Keys obtained from previous The Wild Fairy of Erinnyes quests.
After placing all Teardrop Keys on the statues, a small cutscene will play, and the center of the fountain will reveal an entrance. Jump into the center of the fountain to get to a long underwater tunnel. Keep diving downward until you reach the surface, where you'll find a Luxurious Chrest. Loot the Chest, then enter the portal beside it. Refer to the arrow in the second image above for the location of the portal.
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When the current stops, follow the path lined by underwater rings and use them to guide you toward the entrance to another cave. Refer to the arrow above for the exact cave entrance. The cave will take you to shallow water, where you can then emerge on land.
Once on land, unlock the Hidden Teleport Waypoint for easy navigation later on. Head further into the passage to trigger dialogue with Pahsiv.
From this point onward, you will be faced with tough combat situations. I highly recommend putting together a strong team with a healer or shielder for survivability. The team needs to be strong enough to defeat both Electro and Geo Rifthounds.
You'll be asked to cleanse the filth near the "root." Head into the clearing and start by defeating all the Rifthounds. They'll get in the way and continuously drain your HP, so it's best to eliminate them as soon as possible.
After clearing the Rifthounds, interact with the nearby machine to obtain the Xenochromatic Ball Octopus' ability. Like previous quests in the chain, you need to use it to get rid of the Contaminated Bacterial Mats surrounding the area. I suggest having a shield on as the Mats will attack you.
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The goal is to defeat the Root-Consuming Tumor—the giant rock at the center of the clearing. But it's protected by a shield, which will only disable after defeating the smaller Contaminated Mats. So press and hold the Xenochromatic Ball Octopus' ability to get rid of the smaller Contaminated Bacterial Mats first. When they're gone, you can attack the larger Root-Consuming Tumor using the same ability.
Once the Tumor's HP gets to a certain point, dialogue with Pahsiv will trigger. More small Contaminated Mats will spawn, but your ability will receive a power-up to make them easier to destroy. Follow the same pattern until the Root-Consuming Tumor is gone.
After destroying the Root-Consuming Tumor, you'll enter a battle segment against multiple waves of Rifthounds. Get rid of all the enemies to complete the objective. When done, your character will automatically swim to the surface. Let the current flow without interruption.
On the surface, you'll automatically trigger dialogue with Pahsiv, completing the World Quest. Don't forget to claim your rewards floating on the surface of the water—including a Common Chest, Exquisite Chest, Precious Chest, and two Mora Chests.
For more on the Erinnyes Forest, check out our guides on All Simple Vault Key locations in Genshin Impact and All Genshin Impact Rusty Rudder Questions and Answers here on Pro Game Guides.