Probably no other sea animal has captured our affection and attention like the dolphin. It's intelligence and athleticism has fascinated observers for years. Dolphins seem to exhibit a friendly willingness to co-operate with humans... something very rare in the wild animal kingdom. We think we know them - racing through aquariums and performing at marine parks. But dolphins are more complex animals, with the capacity for language and affection. In DOLPHINS: Tribes of the Sea we travel the world to see how dolphin groups in different locales interact with humans. And we visit researchers as they discover just how intelligent and clever and intuitive dolphins really are.