Inside

This achievement is earned for finding the seventh secret and can be found on Checkpoint 31 or 32

It can also be found in this video, with a text description of its location below
[5:51] - Secret 7 of 13
After crashing through a wooden patch in the concrete ceiling, instead of going to the right, go to the very left of the area in your submarine. Use the charge to hit the pipes twice, then exit the submarine to make the jump to the new ledge and ladder. Climb to the top to discover the secret.
Note: You can also choose Checkpoint 32 and backtrack to this area.

For this Achievement, you want to load up chapter 31. Once you have loaded up the chapter, you want to start heading to the right. Make sure you keep your flashlight on the creature following you each time it moves to stop it from killing you. Once you get far enough right that you go through an opening, you want to hold & aim with towards the plank of wood holding the door open. This will drop the door and lock the creature out. Now head upwards and smash through the planks at the top on the ceiling using the "Hold technique" Once you are out, you want to head all the way to the left until you reach a wall with a ladder above. In order to climb up, you need to break down the above structure by jumping at it using the "Hold " technique. Once you have smashed it down, you will be able to climb up and you will see the collectible to your left. Walk up to it and hold & in order to pull at it and pop your Achievement!

After crashing through a wooden patch in the concrete ceiling, go to the very left of the area in your submarine. Use the charge to hit the pipes twice, then exit the submarine to make the jump to the new ledge and ladder. Climb to the top to discover the secret. Note to self: You can also choose Checkpoint 32 and backtrack to this area.

See the video for the location for the achievement.
Can be found in Chapter 31.


100% Achievement Guide - All in 1 video:

For this achievement you should load the 31 "chapter" by which i mean the 31 dot under the loading option.

OR "Load chapter 32 and walk left to the sub, avoiding having to escape the thing again."
Credit to: Funky Monkee

Then after you escaped from the you will have to go through the ceiling with your submarine.

After you reach the surface go to the left until you reach a wall and jump against the ladder twice with your submarine to lower it, so you can reach it.

Get out, climb up and unplug the machine to get the achievement.

To unlock this achievement, you need to deactivate the 7th orb. To find it quickly, load the 32nd checkpoint (on the beach in front of a door). Instead of opening up the door on your right, go back left in the submarine and keep going left. When you see a a structure with an unreachable ladder, charge 2 times on it with the submarine to destroy the structure and climb up the ladder (to find the orb). Watch the video below:

A Tableau achievement:


Full walkthrough of the game: