Rise of the Tomb Raider: Return to the valley, walkthrough Rise of the Tomb Raider guide, walkthrough
Return to the valley | Escape the Archive, walkthrough
Last update: 07 July 2020
The last part of your escape requires you o stay underwater for quite long, but since you already have the rebreather, there should be no problems with that.
After you exit the water, you will get outside, by climbing over the wall shown in the screenshot.