The mammals, which are celebrated for their playful natures, are developing the skill "just for fun", according to the Whale and Dolphin Conservation Society (WDCS) in Australia.
Dolphin tail-walking has no known practical function and has been likened to dancing in humans.
WDCS researcher Dr Mike Bossley, who has observed Adelaide's Port River dolphins for the past 24 years, said he had documented spectacular tail walking in two adult female dolphins, known as Billie and Wave.
Now four other individuals have been recorded perfecting their walking techniques – Wave's calf Tallula, Bianca and her calf Hope, and calf Bubbles.
Tail walking is very rare in the wild and in thousands of hours of observation only one other dolphin has ever been observed tail walking in the Port River, and then only once.
The Port Adelaide dolphins are now said to be tail walking many times each day.
It is thought the mammals may have learned the remarkable skill from Billie – who spent a short period at a visitor attraction 22 years ago.
Dr Bossley said that the spread of tail walking appeared to be motivated by "fun", but it was also linked to a serious and fascinating cultural aspect previously unseen in the species.
He said: "Culture in the wider sense of the term, defined as 'learned behaviour characteristic of a community', is now frequently on show in the Port River. This cultural behaviour is of great significance for conservation.
"Cultural behaviours in animals have been identified in several species, particularly chimpanzees. However, most if not all the cultural behaviours described to-date have been of a utilitarian nature, mainly to do with obtaining food.
"A well known chimpanzee example is using a twig to extract termites from a nest in the Gombe Stream reserve.
"The only dolphin example seen up to now is in Shark Bay, West Australia, where a small group of dolphins habitually carry a sponge on the end of their jaw while fishing to protect them from fish spines.
"As far as we are aware, tail walking has no practical function and is performed just for fun – akin to human dancing or gymnastics. As such, it represents an internationally important example of the behavioural similarities between humans and dolphins."