You can start this at checkpoint 31.
- You will start underwater in your vessel, make your way to the right continuing through until you reach the girl swimming
- The light of the vessel keeps the girl away, so you need to get on her right side so that you can make your way to the next area and get rid of her
- Once you're on her right side continue on right with your vessel, but keep her to your left side with the light shining at her
- Continue until you go through the big red doorway and when through bash it at the top to close it and lock her out/in
- From here go up and bash your way through the wooden planks in the ceiling a couple of times
- When through head all the way to the left side and up to the surface
- At the surface use your vessel to bash the metal railing just above on the left, do this twice for it to drop down and allow you to climb up
- Exit your vessel and climb up and then head left to find the sphere, pull the cylinder out to gain this achievement
If you need more help with this you can follow my video guide below which starts at this point: