Another fun expansion for the main game. Players building along the edge of the river hexes gain 1 gold point for each road/settlement/town. Each 3 gold points buys you a VP.
At the end of the Delta is a gold nugget if you manage to build a town or settlement on this point you gain 2 gold points instead of 1.
This expansion is quite good but to avoid the "gold rush" effect it works best played in conjunction with the fisherman of catan expansion.
A worthwhile addition to the game if you want to have a different feel to the game.