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"The lesson will be taught in due time, Aloy. Until then, we wait."
This article contains heavy spoilers, and may reveal plot or quest information.

"...A lifetime of failure, as year after year, decade after decade, I hit walls I could not break, doors I could never breach. Until a Nora huntress marched out of the Savage East and... voila! For her, all the deepest secrets of the Earth were laid bare."

Deep Secrets of the Earth is the seventeenth main quest in Horizon Zero Dawn. The ensuing storyline dialogue you will encounter in this mission can be by altered by completing several side missions and the Frozen Wilds storyline before prying open the wood panel covering the vent (when Sylens informs you it is a point of no return). Fully completing each of the following is known to create distinct changes:


After successfully infiltrating the Eclipse base and taking down their Focus network, Aloy makes her way to Sunfall, the Shadow Carja capital. There she hopes to find more answers about Elisabet Sobeck and Project Zero Dawn.

Entering the city, Aloy looks down from a balcony into the Sun-Ring where a number of Shadow Carja soldiers are attempting to handle a Behemoth. Sylens welcomes Aloy to the Citadel. In the courtyard, Aloy is ushered into the throne room along with a crowd of mercenaries who have gathered to hear High Priest Bahavas announce the day's bounties. As Bahavas announces a bounty on a man named Uthid, a woman approaches Aloy in the crowd, telling her that she wishes to meet with her in Shadowside. As the woman takes her leave, Sylens informs Aloy that the entrance into the Old Ones facility is behind her.

Scaling the rock formations, Aloy finds a covered vent on the other side of a tower. Entering through the vent and descending deeper into the earth, Aloy comes to the door of the facility. While her genetic identity is confirmed and access is authorized, there is a malfunction that bars the doors from opening. She authorizes an emergency venting procedure and the doors open, but a loud mechanical noise alerts the Shadow Carja Kestrels to something amiss in the ruin.

With little time to explore, Aloy begins exploring the Project: Zero Dawn facility. She enters a holographic theater and a message from General Herres of the Old Ones' U.S. Robot Command explains the true purpose of Operation: Enduring Victory. He reveals that Zero Dawn was not a top-secret superweapon program that would save humanity, as it was purported to be. In reality, the Faro Plague had become too advanced for it to be stopped, and the extinction of all life on Earth was inevitable. Operation: Enduring Victory was implemented purely to buy time for Elisabet Sobeck and her team to finish Project: Zero Dawn.

Continuing on to the next room, Aloy discovers that some Kestrels have entered the facility. After killing them and scanning the datapoints, Aloy continues on to find another theater with a hologram message left by Elisabet Sobeck who finally explains what Project: Zero Dawn is: a terraforming system controlled by an artificial intelligence unit called GAIA. Through GAIA and her sub-functions, the artificial intelligence would shut down the FARO robots and eventually reform the earth to re-create humanity. Aloy takes out more Kestrels and restores power to an ancient door to reach Central Projects.

Central Projects

After killing the waves of cultists that descend into the room, she heads for the second floor. As she passes through the vast rooms she is introduced to a few sub-functions of GAIA, learning their functions through holographic messages left by the Old Ones. She eventually comes to a room where Travis Tate explains the purpose of HADES; a failsafe system that would seize control of the terraforming system in the event that GAIA produced a world that was unsustainable or uninhabitable, deconstructing the world so that GAIA may try again. After learning about ELEUTHIA from a hologram of Patrick Brochard-Klein, Aloy deduces that All-Mother mountain must be one of the Cradles created to produce humans.

Dr. Sobeck's office and the Alpha Registry

Climbing up the elevator shaft, Aloy comes to a room with a number of datapoints containing interactions between Elisabet and an early GAIA as well as Ted Faro. Prying open the door to Sobeck's office, Aloy finds and copies the Alpha Registry master file that will allow her access to the facility in All-Mother mountain. As Aloy and Sylens argue about her origins, more Kestrels descend outside the office, including Helis who throws a blast bomb. The explosion stuns Aloy, allowing Helis to approach her and knock her unconscious.

Some time later, Aloy awakens to find herself unarmed and unarmored, suspended in a cage above the Sun-Ring. Helis approaches, telling her that before she crashed the Eclipse network, he sent an order out to rally the Eclipse to invade the Sacred Lands. He then destroys her Focus. Now addressing the crowd, two Corruptors enter the Sun-Ring and begin corrupting a restrained Behemoth. Condemning Aloy to be the first of thousands to die, she is dropped into the Sun-Ring to face off against the machine


  1. Go to Sunfall
  2. Go to the Citadel Courtyard
  3. Enter the Citadel
  4. Go to the Grand Balcony
  5. Climb down
  6. Use the Secret Entrance
  7. Explore the Project: Zero Dawn facility
  8. Enter Viewing Room
  9. Kill the Shadow Carja
  10. Enter Viewing Room
  11. Go to Processing
  12. Go to Central Projects
  13. Restore Power to The Door
  14. Enter Central Projects
  15. Kill the Eclipse
  16. Find the Entrance to Sobeck's Office
  17. Examine Elisabet Sobeck's Terminal



Deep Secrets of the Earth - Very Hard - No Damage - Video Guide



The following datapoints are obtained automatically during this quest and cannot be missed.

Hologram Datapoints


In addition, the following datapoints can also be found inside the facility during this quest. The player can return at any time if they are missed.

Audio Datapoints

Hologram Datapoints

Text Datapoints - Quests


  • If Traitor's Bounty and Queen's Gambit are completed before this quest, Helis will comment on the death of Bahavas and disappearance of Itamen and Nasadi.
  • Aloy will mention seeing "Stalkers. Ravagers. A Thunderjaw." in Cauldrons, even if the player has not completed such Cauldrons yet.
  • Stranded shackles can be found inside the facility
Horizon Zero Dawn Quests
Main Quest A Gift from the Past - Lessons of the Wild - The Point of the Spear - Mother's Heart - The Proving - The Womb of the Mountain - A Seeker at the Gates - The War-Chief's Trail - Revenge of the Nora - The City of the Sun - The Field of the Fallen - Into the Borderlands - The Sun Shall Fall - Maker's End - The Grave-Hoard - To Curse the Darkness - Deep Secrets of the Earth - The Terror of the Sun - The Heart of the Nora - The Mountain That Fell - The Looming Shadow - The Face of Extinction
Side Quests A Daughter's Vengeance - A Moment's Peace - Acquired Taste - Ancient Armory - Blood on Stone - Cause for Concern - Farewell - Death from the Skies - Fatal Inheritance - Heap of Trouble - Honor The Fallen - Hunters' Blind - In Her Mother's Footsteps - Insult to Injury - Queen's Gambit - Redmaw - Robbing the Rich - Sun and Shadow - Sunstone Rock - The Forgotten - Traitor's Bounty - Underequipped - Weapons of the Lodge
Errands A Curious Proposal - Collateral - Deadliest Game - Demand and Supply - Hammer and Steel - Healer's Oath - Hunting for the Lodge - In Foreign Lands - Luck of the Hunt - Odd Grata - Sanctuary - Shortage of Supplies - Sun's Judgment - To Old Acquaintance
Activities Bandit Camps Blackwing Snag - Devil's Thirst - Gatelands - Hollow Fort - Shattered Kiln - Stone YieldFW - Two-Teeth
Cauldrons Cauldron RHO - Cauldron SIGMA - Cauldron XI - Cauldron ZETA
Corrupted Zones Corrupted Zones
Hunting Grounds Greatrun - Nora - SnowchantsFW - Spurflints - Sun Furrows - Valleymeet
Tallnecks Devil's Thirst - Copper Deeps - FrostfiguresFW - Rustwash - Spearshafts - Sun-Steps
Horizon Zero Dawn: The Frozen Wilds Quests
Side Quests Firebreak - For the Werak - Frontier Justice - Into the Frozen Wilds - The Forge of Winter - The Hunters Three - The Shaman's Path - The Survivor - Waterlogged
Errands A Secret Shared - Ikrie's Challenge - Geared Up: Forgefire - Geared Up: Icerail - Geared Up: Stormslinger - Out of the Forge - The Claws Beneath