Crossing the river | Mission 5 - Lady Boyle's Last Party Dishonored Guide
Last update: 11 May 2016
It is compulsory to reach the other bank of the river, because this is where the Boyle Estate is located. The most obvious variant is to take the metal bridge located near the starting point (the above screenshot)
Another interesting solution assumes that you reach a bigger bridge. It is located further away from the Estate, and you would have to avoid the guards described in the previous subsection.
The least obvious variant is to use Blink (teleport) in the area in which both banks are the closest to each other, i.e. to the left of the big bridge (the above screenshot). It's is the best path to follow if you do not intend to attack anyone.