The Cosmic Abyss Chapter 3 Ritual Puzzle Guide

Developed by The Big Bad WolfCthulhu: The Cosmic Abyss is an investigative title that relies heavily on complex puzzles from the first second. So if you find yourself stuck in the first game, don’t feel bad, because it’s totally on purpose!
The developers designed these challenges to make players really stretch their brains. While the first two chapters already demand a Sherlock Holmes level of intuition, Chapter 3: The Temple it’s the first to prove that focusing on atmospheric pressure and solving puzzles is real here.
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That’s because this chapter puts you in the middle of a culture going on in R’lyeh, the sunken city, and requires you to complete it yourself. To succeed, you must overcome a series of complex puzzles in a certain order and learn to translate the R’lyehian language.
But don’t worry – this guide will help you explore the mysteries of the third chapter and explain all the necessary steps in the most straightforward way possible.
How to Remove the Battery and Turn on the Computer
As soon as the chapter starts, you will have three options to choose from: left, right, and straight forward in a small area. Your first priority should be to find a way to access the computer that is located on the right side of the altar (this is the man that is attached to it), which is sitting on top of a crate.
Contact the device to find out if it belongs to you Anastasia Wolejkoone of the main scientists of Ocean-I, and that it contains his research on The R’lyehian language. Since almost all the important texts here are written in that language, and you’ll need to understand it to progress, translating it is your first big task here.
However, the computer is dead, which means you need to get an external battery to wake it up. You will see that the battery is already connected, but it is covered by something strange. Upon analysis, you will find that it is rusted and full Helium again Potassium Hydroxide. These two elements will be automatically added to your Sonar, and this will become very important soon.
Now, follow the path behind the altar to find a small Ocean-I camp with some crates inside. Open the one on the left to find more batteries, but analyzing them reveals that they are full Lithium instead of Helium, which means something unusual is happening to the machines here.
Right in front of the camp, there are two tables. Contact the one on the left (in front of the tomb) to find a letter that explains that batteries corrode and don’t work whenever they are near metal.
With this information, you can find out you need a working battery that contains only Lithium and Potassium Hydroxideso activate these two elements on your Sonar and scan the campsite for a working battery! Return it to the computer to unlock Anastasia’s research, eventually allowing you to read the mysterious temple texts.
Ending the Tradition: The Three Ancient Crowns
Once you can translate the script, it’s time to complete the ritual that the members of Ocean-I started before they lost their minds. The practice consists of three steps: to find three ancient crownsHe blessed them and placed them on the bones that sat on the thrones.
Fortunately, two of the three crowns are easily found, because they are “hidden” in the first place. I the first is behind the main altar on the floorand the second is on the table in that camp where we found the battery. The last one is hidden in the left column, so we will find it later.
Before proceeding to the right path, notice that behind the rock holding the pain man, there is a small pool of blood that you can’t interact with. This is where you have to bless the crowns by dipping them in blood! So take the two crowns you just got and wash them in this blood before moving on.
How to Pass the Hall of Secrets
When you take the path to the right of the altar, you will find yourself at the altar Hall of Secrets. This is basically a dungeon where you have to choose the right path to progress, but there are only two ways: forward or turn.
An audio log in the area reveals a conversation between members of Ocean-I, stating that Anastasia actually found a way to beat the maze by studying the graves near the camp, which contain some writing in an ancient language.
Since you already have the R’lyehian translation, go back to that same camp from before and interact with the tombs (only two of them, since the third one is broken). By doing so, you will discover that the secret to defeating the Secret Hall lies in the bas-reliefs on the walls.
Summary: in each section of the maze, check the bas-relief on the walls. If there is, move on. If not, repent. Repeat that trick until you reach the end of it.
Just be sure to interact with the entire bas-relief as it explains the ritual behind the ritual we are doing! If you did everything correctly, you will reach the end of the hall, where a skeleton on a throne awaits. Check the Ancient Eye Crown (check it in your inventory to make sure it has an eye symbol), then place it on your dead friend to complete the first step.
How to Get Through the Pool of Blood
Return to the altar. Before taking the left path, be sure to analyze both your remaining ancient crown and the blood of the altar, as this registers. Ancient Blood again Orichalcum on your Sonar. So open them up and scroll down to the left column from the main area.
You will find yourself in a place full of blood and a body that looks like it was sacrificed in the middle. Next to this sacrificial corpse, you will see two scary sculptures on either side of the wall. So head to the one on the right, where the water is deep enough to swim, and dive to find a secret passage. Your Sonar is your best friend here, as that combination of Ancient Blood and Orichalcum will point out the last one missing is the Ancient Crown and allows you to see through murky, blood-stained water.
In the first underwater area, you can look up to find some corpses to analyze and a small structure to climb. Follow it to the end and jump down in front of the open tomb to reveal another secret passage. Swim through the Sonar to find the Last Ancient Crown, which has a claw mark on it (don’t forget to analyze it!).
Now, exit this area and return to the blood area, looking for an underwater staircase to follow that leads to the second skeleton on the throne. This skeleton needs the ancient crown you just took, but you need to bless it first, remember? So head to the exit (in front of the throne) to find a locked door that requires a round object to open – luckily for us, it’s on the ground where you’re standing now, next to a corpse and a sound log.
Grab it and open the door to find yourself back in that original area with blood (and a sacrificial corpse). Simply return to the altar to bless the last crown with blood and place it on top of the bones to complete the second major step.
How to Start a Culture
By placing the second ancient crown on the skeleton, green slime will appear throughout the temple, especially in the main area with the altar. Go back there to find out another skeleton sitting on a throne in the centerand uncomfortable proof that the ritual works, as the man trapped at the altar will be worse off than before.
Now, all you need to do is place the remaining Ancient Crown, the one with the Tentacles, on the skeleton that just appeared. Doing this will eventually start a ritual, completing Chapter 3 and opening the way to the portal. Oh, and you’ll also meet the Deep One, one of the creatures that will appear again and again from this point forward.
- Released
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April 16, 2026
- Number of Players
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Single player
- Steam Deck Compatibility
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Not known
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