Instructions
Head to Millfields and speak to the entrepreneur on top of the hill, if you have not already talked to him. Give the man 750 gold coins to build a bridge from the hill to Driftwood.
Enter Driftwood and talk to the settlement leader, who is standing on the beach, to get the Pest Control quest. Follow the path and kill every monster you see. When you get the notification that they are all dead, return to the man to complete the quest.
Go to the Bowerstone Market and speak to a man named Rusty to get the An Island Getaway quest. Hold Rusty's hand and lead him back to Driftwood to complete the quest.
Speak to the Driftwood settlement leader to receive the Gift Wood for Driftwood quest. Travel to Silverpines and make your way down the path.
Kill any balverines that get in your way. Continue following the path until you see a cottage. Kill the enemies here and enter the cottage. Give the letter to the carpenter to convince him to leave and go to Driftwood.
Return to Driftwood. With all three quests completed, you now have access to all the islands. Walk out to the main island and shoot the switch there. Follow it across the islands, shooting the switch as you move.
Cross the bridge to the final island. When the switch lands there and turns blue, hit it with your melee weapon to open a portal. Enter the portal and pick up the gold key that is floating in front of you.