The expansion is about fishermen. Some of the sea tiles of the base game are transformed into Fishing Grounds. These Fishing Grounds produce resources in a way similar to regular tiles.
Instead of Resource Cards, Fishing Grounds provide Fish Tiles. Fish Tiles can be worth one, two or three fish.
During his turn, a player can spend fish to get a special benefit:
2 fish: The player may move the robber back into the desert (he/she may not steal a card from another player who owns a settlement / town at the desert).
3 fish: The player may steal a raw material card from another player.
4 fish: The player may take any one raw material from the bank.
5 fish: The player may build a street immediately.
7 fish: The player receives a development card for free.
In addition to fish, a player can also catch an old shoe. As long as a player has the old shoe in his possession, he needs one more point to win the game than usual. He can get rid of the old shoe by giving it to someone with the same number of points or more points than himself.