1. Potomac   Washington D.C.   Cologne   Montreal   Bern   Hint Half-n-half Clue   2. Spree   Berlin   Lisbon   Bern   Rome   Half-n-half Clue   3. Nile Nile Blue Nile   Paris   Vienna   Bern   Cairo   Half-n-half Clue   4. Seine   Kinshasa   Paris   Vienna   Washington D.C.   Half-n-half Clue   5. Ottawa, St. Lawrence Ottawa St. Lawrence Outaouais   Montreal   London   Berlin   Cairo   Half-n-half Clue   6. Danube   New York   Vienna   Cairo   Cologne   Half-n-half Clue   7. Hudson   Kinshasa   Cologne   Montreal   New York   Half-n-half Clue