Singer-songwriter Cerys Matthews follows the trail of 'Ol' Man River'. "The Mississippi is very special," says Cerys, who lived in Nashville, Tennessee for nearly six years, becoming familiar with the river's lower reaches.
Today the Ganges, though holy, is less than pure. Ifor ap Glyn follows the river and meets some of the people that depend on it.
Bethan Gwanas travels along the Yangtze river to see the Three Gorges Dam that has tamed the destructive force of the river and changed the lives of the people that live on its shores.
Aled Sam follows the Nile through Egypt to its source in Ethiopia where a new dam is being built.
Iolo williams journeys along the Amazon and looks at the commercial development that is killing the wilderness which protects the river and puts its future in the balance.
Mererid Hopwood journeys along the Rhine which is the great artery at the heart of Europe and meets some of the people who's lives depend on it.
© 2012 S4C
O Gymru / Made in Wales