Castles by the Sea: Riptide Expansion introduces a new mechanic to the base game.

The Riptide Expansion is played exactly like the base game, but with one addition to the Hazard step. At the end of each player's Hazard step, they must roll the Tide Die and move the tide around the board!

This expansion can be mixed with the base game components, and includes options for prebuilt Kingdoms.