Papyrus Riddle: In Plain Sight
This riddle is in the Palace of Apries in Memphis.
"On an island south east of Krokodilopolis there is a river with unnatural color. Nearby you'll see the cause, and I'll be inside the only one that's unique." The text is clear, this solution is on the southeastmost island of the Krok cluster.
The solution is in that odd silver-gray pit in the middle.