The Innkeeper's Husband in No Rest for the Wicked - How to Pass

To find the key to the western bridge, you must first start the quest "The Innkeeper's Husband". You can get it from Cassandra inside Sacramenta. Once in town, go downstairs (turn right on the road) and look for the seated painter. Above him on the screen is a woman (in the ruins of a building). Talk to her to start an additional quest. Until you do this, the key won't appear!

Now go back to the starting point after the shipwreck and go west of the beach. Climb to the top of the ruined tower, then jump across the chasm - to where the innkeeper's husband is. On the corpse next to the husband should be the key to the west bridge.

To get to the west bridge, go back and climb the tall tower on the far western edge of the Sea Fortress. At the top level, there will be a wooden door leading to the west bridge. You can now open it. There are several enemies in the area of the west bridge, including a heavy knight with powerful sprawling attacks. However, there are also a few chests to search and places to dig (you will need a shovel).