Get back on the Dreadful Wale | Mission 3 Dishonored 2 Guide

Start with eliminating the enemy located near the railing.

The last part of the objective is the escape from Addermire Institute. In order to do so, head to the ground floor and use the back door where you will stumble upon three guards. One of the guards, shown on the above screenshot, will be facing you with his back - start by eliminating this foe. Hide the body of the victim in the bushes around the corner, so that the enemies won't notice what happened.

The next two guards will be hard to eliminate, as one of them, the elite one, will be sitting at his position and looking at your direction all the time. You must be creative and either use bottles and/or glasses located on the right side, or put the guard to sleep with a Sleep Dart.

Use Blink to get behind the guard.

Regardless of your choice, head to the place shown on the above screenshot and locate the second guard. If the guard will be facing you with his back, quickly incapacitate him. It's hard to accomplish, but it can be done without losing Ghost status.

Jump on top of the platform and cut off the power, allowing Maegan to swim to the shore.

After eliminating the enemies jump on top of the tower shown on the above screenshot, take out the whale oil container to cut off the power. This will allow Maegan to swim to the shore. There are some enemies and treasures located below your current position, but you won't have any problems with eliminating the first and collecting the latter.