To Bernard Thomas, sustainability is a way of life. Thomas builds his own small boats called coracles, and he fishes for local salmon on the Teifi River near his home in rural West Wales. The coracle, which is still made using simple hand tools and natural materials such as split ash and pitch, dates back to prehistoric times when it was shaped from cowhide. Thomas, 85, is considered "the keeper of the river," and today is visited regularly by people from as far away as New Zealand who wish to learn the secrets of building their own coracle.

To Doncasters, a large multinational corporation, sustainability is smart business. The Blaenavon, ...