We cover the two climatic extremes of North America: tropical Mexico in the far south and arctic Alaska in the far north. Warm Mexico bears witness to ancient cultures in the form of well-preserved ruins, and is home to two of the world’s greatest migrations: those of the monarch butterfly and grey whale, whose remarkable journeys can only inspire awe. Cold, contrasting Alaska with its brown bears, orcas, puffins and humpbacks is best seen from one of our small cruise ships which ply the fjords and islands of the USA’s forty-ninth state.