The large, locked chests that appear in dungeons are all opened with the same key, but obtaining the key won’t be easy. The rewards from the quests in Pawt City include the ability to walk on water. Once you can walk on water, go southwest from the Catpital to a wreck. From the wreck, go south until you reach Founder’s Island. Check the quest board and accept the quest titled Golden Key. The dungeon for the quest is filled with dangerous mimics that resemble treasure chests. If possible, tackle the mimics individually. Take out the smaller mimics before you attempt to tackle the big one. After you obtain the key, return to the dungeons with golden chests (the entrances will be marked) and claim your prizes.
