At CHECKPOINT 11, just below the grating in the floor, you can see a sparkling reward.
Jump into the water. Swim against the current (tap Interact to swim faster) into the space below the grating to get the bronze reward (8/9).
Surface for air and then swim across the passage to pull the underwater lever on the opposite wall. This opens the gate to the right, where you'll find another floating coffin.
Swim to the coffin and climb on top of it.
As the current carries the coffin along the passageway, jump into the opening above on the right.
If you miss it, climb back onto the coffin and use the grapple to hook one of the wall sconces. Then pull the coffin, with Lara on it, back to the opening and try the jump again.
Hop down into the water on the other side. Swim forward, then turn left.
Swim forward toward another metal gate, then turn left again.
At the end of this passage is yet another gate, beyond which you can see the coffin Lara was just riding. On the right, just below the surface of the water, is another lever. Pull it to open the gate.
[Part 2 | Return to the England Walkthrough]