Horizon Forbidden West The Sea of Sands Walkthrough

The Sea of Sands is the 11th Main Story Quest in Horizon Forbidden West (HZFW). This walkthrough will guide you through all objectives of the The Sea of Sands main mission.

Starting Location: The Base
Quest Giver: GAIA (automatically triggered upon completing Cradle of Echoes)
Quest Level: Level 22
Requirement: having completed Cradle of Echoes
Reward: +12000 XP, +2 Skill Points
Mission Info: In pursuit of POSEIDON, one of GAIA’s lost subordinate functions, Aloy must journey through a vast desert to reach the ruins of Las Vegas.

Objectives:

• Go to POSEIDON’s Coordinates
• Search the Ruins for a Way Underground
• Investigate the Flooded Ruin
• Gather the Machine Parts – Go to the Machine Herd
• Gather the Machine Parts – Search for Tracks
• Gather the Machine Parts – Follow the Tracks – Kill the Machine Herd (Optional)
• Gather the Machine Parts – Follow the Tracks
• Gather the Machine Parts – Kill the Machine Herd
• Recover the Compressed Air Capsule
• Return to Morlund
• Craft the Diving Mask
• Find POSEIDON
• Find the Red Light
• Investigate the Red Light
• Drain the City – Find the Primary Pump Node
• Drain the City – Activate the Primary Pump Node
• Drain the City – Find the Secondary Pump Node
• Drain the City – Activate the Secondary Pump Node
• Drain the City – Return to the Sunken City
• Drain the City – Find the Pump Maintenance Station
• Drain the City – Find an Entrance to the Pump Maintenance Station
• Drain the City – Activate the Emergency Purge
• Find POSEIDON
• Kill the Tideripper
• Find POSEIDON – Talk to Morlund and His Crew (Optional)
• Recover POSEIDON
• Return to the Elevator Shaft
• Climb to the Surface
• Exit the Ruin
• Return to the Base
• Deliver POSEIDON to GAIA

Starting Location: The Base

 

Go to POSEIDON’s Coordinates

Leave the Base and start heading south for the ruins of Las Vegas. You could potentially run into the Stillsands Tallneck on your way to the south. It’s worth overriding it to defog more of the map.

Search the Ruins for a Way Underground

Once at the location, you need to find a way to access the ruins underground over a vast investigation area. The access area is shown in the map and in-game screenshots below. Once you approach it, the game will trigger the next objective.

Investigate the Flooded Ruin

Enter the flooded pagoda using the ladder and enter the camp.

Gather the Machine Parts – Go to the Machine Herd

Exit the camp and head further south to the Machine Herd to recover the parts you need.

Gather the Machine Parts – Search for Tracks

Activate your Focus to highlight the tracks ( ) in the middle of the ruined arena.

Gather the Machine Parts – Follow the Tracks – Kill the Machines (Optional)

Now, while in Focus view, highlight the tracks, exit back out of the Focus view and start following them. At the end of the tracks, you’ll come across a herd made up of different machines: Purgewater Canister Burrowers and a Frost Glinthawk. If you want, you can ignore them, but we suggest defeating them for materials.

Gather the Machine Parts – Follow the Tracks

After ignoring or getting rid of the machines, reactivate your Focus to re-highlight the tracks and follow them from around the ruins. They will be shown by purple triangles and head for the location shown below.

Gather the Machine Parts – Kill the Machine Herd

You’ll soon encounter a new herd made of different machines: Longlegs, Lealpashers, and Frost Bellowbacks. This time you have to kill the machines. Identify their weaknesses and plan accordingly. Once you’ve gathered what you need you can return to the camp to recover the second part, the Compressed Air Capsule.

Recover the Compressed Air Capsule

At the camp, enter the water shaft and dive down halfway through it to acquire the Compressed Air Capsule. You need to be quick, it’s far down and you’ll run out of breath if you take too long.

Return to Morlund

Now swim back up and return to Morlund to tell him you’ve got the parts.

Craft the Diving Mask

Approach the workbench by Morlund to start crafting the Diving Mask, a special breathing apparatus that enables diving to extreme depths and without having to resurface for oxygen.

Find POSEIDON

With our new breather, let’s go search for POSEIDON. Dive down into the water where you got the Compressed Air Capsule. Keep swimming through the open doors. There’s only one way forward here. You dive down with and up with and can speed up by pressing . Eventually, you’ll come across a Tideripper machine (don’t forget to scan it) in a massive dome-like area. From the door you came in, the left side has too strong a current for Aloy, so we need to head for the right side. POSEIDON is below the giant hole in the ground, but before being able to access it we need to remove the current and especially get rid of the Tideripper.

Find the Red Light

As you swim your way to the right side of the dome, head for the red light.

Investigate the Red Light

Approach the red light and pull the switch to drain the water.

However, something has gone wrong and we first need to fix the pump nodes.

Drain the City – Find the Primary Pump Node

Swim back up and around and keep heading to the waypoints while hiding from the next few machines, specifically a Snapmaw (don’t forget to scan it).

Enter the pipe and keep swimming down until you reach a room where you can swim back to surface.

Instead of doing so, stay underwater and go left from the way you came in, then resurface to spot a ladder to climb.

Drain the City – Activate the Primary Pump Node

Now run back around to access the valve and open it.

Drain the City – Return to the Sunken City

Make your way back to the sunken city now. We need to go for the second node.

Drain the City – Find the Secondary Pump Node

Once you’re back in the sunken city, follow the waypoint that leads to the second node, again try to avoid the enemy machines.

 

Drain the City – Activate the Secondary Pump Node

At the end of the path, swim back to the surface and make your way to the valve by means of the yellow ladder.

This valve won’t budge though and has to be loosened. There’s some Firegleam on the rusty bridge that you can destroy (beware, it explodes), making it then possible to budge the valve.

Drain the City – Return to the Sunken City

Now make your way back to the sunken city and head for the Pump Maintenance Station.

Drain the City – Find the Pump Maintenance Station

Follow the waypoints to get to the general area of the Pump Maintenance Station.

Drain the City – Find an Entrance to the Pump Maintenance Station

The entrance to the Pump Maintenance Station is located between some rubble next to the Pump Staton tower. The in-game screenshot below shows the exact location to its entrance.

From there swim down and open the doors. Keep swimming along the main path through the doors until you reach a third and final door to open.

Drain the City – Activate the Emergency Purge

From here, swim up to reach the console panel and activate the holo projector that will drain the place.

Find POSEIDON

Now we can resume our search for POSEIDON. Backtrack to the dome area and follow the waypoints.

Kill the Tideripper

The Tideripper is a giant dragon-like machine. Its weaknesses are Shock and Frost Damage, so prioritize these elements against it. It also has a weak spot near the front fins and halfway through its body. You can scan the machine at the beginning of the fight to find a highlight the weak points.

Find POSEIDON – Talk to Morlund and His Crew (Optional)

Feel free to talk to Morlund and his crew if you’d like, or immediately head for POSEIDON. Open the door and continue on until you access a server room. At the end of it is POSEIDON.

Recover POSEIDON

Simply insert GAIA Kernel into POSEIDON to recover it.

Return to the Elevator Shaft

Make your way back to the area where you fought the Tideripper and use the yellow ladder to quickly go up.

Then, access the building and go to the second floor to find a ladder that leads you further up.

In the next area, run back around to the elevator shaft.

Climb to the Surface

Activate the elevator to return to the surface.

Exit the Ruin

Finally, exit the ruin.

Return to the Base

Time to return to the Base and give POSEIDON to GAIA. You can use the campfire to fast travel back immediately.

Deliver POSEIDON to GAIA

Return to GAIA’s room to add POSEIDON to her matrix.

This finishes The Sea of Sands Main Quest in Horizon Forbidden West.

For all other Side Quests and Main Quests, check out the complete Horizon Forbidden West Walkthrough.