Exploring the second part of the sewers | Mission 7 - The Flooded District Dishonored Guide
Last update: 11 May 2016
New Main Quest: Unlock Sewer Gate
Reach the upper ledge, approach the locked gate and use the key that you obtained from Granny. After the gate is open, you can go on.
After a while, you will reach a camp occupied by friendly civilians. This does not mean, however, that you can feel safe here, because you need to eliminate river krusts attached to the ceiling (the above screenshot). After you dispose of the creatures, explore the area for gold, food, bolts, <br>a grenade, two Sokolov's health elixirs and a rune.
Continue along the sewers on a linear path. On your way, there are wooden boards to smash and further river krusts to eliminate. You should also watch out for piranhas in the water. Take a look around the cave to find two Piero's spiritual remedies and a bone charm.
In order to unlock a path further, you need to smash the planks shown in the above screenshot. In the last area of the sewers, you can find gold, food and bolts. Go to the door marked by the game. Interacting with it equals being promoted for the next stage of the game.