From the publisher's website:-
'Introducing to the world of Catan, The Great River of Catan! A unique, three-tile, die-cut piece that brings the excitement of the gold rush to your The Settlers ofcatan game and your Cities and Knights or Seafarers as well. This new variant includes: 1 three hex river tile to fit your base game, 10 new number counters, and special rules.
The Great River of Catan challenges Catan fans to race for the gold by building settlements and roads alongside the river tile. Those who build along its banks stand to profit from the gold craze sweeping the land, for they will receive gold for each settlement and road they build on the river. Once players have accumulated sufficient gold they may exchange it for victory points! '