Objective: Find a way out of the archives with the Atlas
Enter the water and proceed through the tunnel until a scene plays. Following the scene, you’ll find yourself underwater. Simply spam the swim fast button whilst following the set route that the game provides for you until another scene triggers.
We’ll now have access to a new piece of gear: The Rebreather . This will enable Lara to stay underwater indefinitely without running out of oxygen.
Swim through the tunnel ahead, taking the linear path through the obstacles until you are able to surface. Swim to the end of the passage here to find some dry ground and scramble up the left hand wall to enter the next large room.