The investigation and deduction-based gameplay of Cthulhu: The Cosmic Abyss lends itself to some fun and sometimes challenging trophies/achievements. Although while you’re busy tracking down a missing deep-sea mining crew and dodging Deep Ones, it’s not always easy to keep track of them. So, here is our In Deep Waters trophy/achievement guide for Cthulhu: The Cosmic Abyss.
Check out our Cthulhu: The Cosmic Abyss Review for our full thoughts on the game.
In Deep Waters Trophy Guide
The In Deep Waters trophy/achievement is unlocked during Chapter 3, The Temple, and requires you to restore the seal and destroy the Deep One using the Low Corruption Path. This is also helpful if you are looking to unlock the Mens Sana trophy/achievement for finishing the game without exceeding the corruption threshold.
Once you have found David Curwen fused to R’lyeh as part of a ritual, look behind them to find a pool of water down some stairs. Next to the pool of water is a round metal plate to analyse, unlocking the Unknown Alloy frequency.
Head back up, and go through to the other half of Camp Mu you haven’t seen yet, and pick up the strange cube on the table.
Next, walk up the ramps you walked under to reach the rest of the camp and drop down to break through the floor below. (There are notes and a Deduction that explain that some ground is brittle due to invasive algae, but you can break through the floors without knowing this.)
You’ll be in a partially submerged chamber with a large machine in its centre, under the water. Analyse it to unlock the Electrum frequency. Equip this new frequency and use it to find the piece of the machine that has fallen off. Pick it up and put it back in the machine to get it working again.
Swim up and climb onto dry land to see another of those metal plates emitting strange signals. Follow the only way out back up to where David Curwen is in the central chamber, and go to the right of him through the door before the staircase to reach the Antechamber.
The solution to passing through the Antechamber, or the Hall of Secrets, is to move forward through the chamber when there is something to learn, i.e. a mural on the wall to look at, and to turn back when there is nothing new to see. (The clue to the related Deduction can be found on the middle tomb just below where the pool of water is.)
You can also use the Unknown Alloy frequency to track the Relays, or just follow the signal, to make things easier.
Eventually, you’ll reach a chamber with a skeleton sitting on a throne in the middle. Switch to the Unknown Alloy to locate a second cube in the water beneath another metal plate on the back wall of the room.
Walk up the ramps to reach the metal plate on the wall, and take out one of the cubes you carry. Switch back to the Electrum frequency and use the sonar to watch the cube transform into a sphere. Quickly insert the sphere into the metal plate to activate it.
Return the way you came to reach the central chamber, and go through the doorway on the opposite side to reach a large chamber filled with red liquid.
To the right of the sacrificial altar is an underwater passage you need to swim through (use your sonar to improve visibility). Equip the Unknown Alloy frequency to locate the next metal plate/cube combo, and head towards them into another long chamber.
Grab the cube and use the Electrum frequency to transform it, and insert the sphere into the metal plate, activating the second plate.
Now you can swim back the way you came, or swim to the surface to climb onto the long platform with another seated skeleton. Opposite the skeleton is a locked door with a round mechanism next to it. Look for a small, round object next to the dead body and insert it into the mechanism’s recess to unlock the door, leading to the sacrificial chamber.
Walk back through to the central chamber and down the stairs to the metal plate near the pool of water. Pull out the third and final cube you found and use the Electrum frequency to transform it into a sphere.
Slot it into the metal plate to restore the seal, watch the in-game cutscene, and unlock the In Deep Waters trophy/achievement. As part of the Low Corruption Path, this will lower the Corruption you have incurred.
That was our In Deep Waters trophy/achievement guide! We hope it was helpful, and you can find more guides for Cthulhu: The Cosmic Abyss below.
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Cthulhu: The Cosmic Abyss Guides
- 100% Trophy Guide
- Augmented Agent Trophy Guide
- Full Charge Trophy Guide
- Artist Trophy Guide
- Against The Tide Trophy Guide
- Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn Trophy Guide
- Linguist Trophy Guide
- Beyond The Senses Trophy Guide
- His Master’s Voice Trophy Guide
- Open Sesame Trophy Guide
- Where Am I? Trophy Guide
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