Between Shadris and Sorlet (Might and Magic: Heroes 7)

At the beginning of the map (for the forest union), the pirates in the bivouac saw such a message https://yadi.sk/i/hYxwyVWymkcap Question: What kind of treasure are we talking about, has anyone figured it out? Maybe it's the sequence of overcoming the whirlpools, because to the west of Shadris I don't see any treasures (maybe there is something smart there).