You need to travel the three sand isles and go to see Dusty, who will send you to Dust Isle. On Dust Isle, find Fitzgerald (the old man) and ask him to send you to Renard the Fox on Aesop Isle.
Renard will send you back to Fitzgerald, Fitzgerald will send you back to the Sand Isles. Stay on that sand isle but go to the bridge - there is a palm tree just below. Use your tools around there and you will find the box.
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