Visitors to Glenelg have been treated to a remarkable animal encounter, with a curious black labrador spotted frolicking in a popular Adelaide river with a playful dolphin.

Key points: The footage shows the dolphin leap into the air over the labrador

The footage shows the dolphin leap into the air over the labrador An expert says it is not uncommon for dolphins to be curious of other animals

An expert says it is not uncommon for dolphins to be curious of other animals He says Adelaide has a rich history of interesting dolphin encounters

Footage of the Sunday encounter was uploaded on social media on Monday, with the video showing a labrador swimming to the middle of Patawalonga Creek at Glenelg, in Adelaide's west, when a dolphin seemingly decides to join in the fun.

The dog seems to follow the dolphin at first near the edge of the creek before losing it to the deep water.

But that is when the playful sea creature returns to swim by the labrador's side near the middle of the creek, speeding up and leaping into the air over the playful pooch's head.

The footage was posted by Adelaide's Billie-Michelle Eastwood, who said the encounter was "incredible to watch".

Ms Eastwood told ABC News that she spotted the encounter about 8:00pm and that the dog swam with the dolphin for about half an hour.

"I was completely surprised … I could see the dog wagging his tail so it definitely seemed as if they were just playing together," she said.

The dolphin was captured leaping over the labrador. ( Facebook: Billie-Michelle Eastwood )

"The dog was swimming towards the dolphin the majority of the time and looked happy as Larry."

Ms Eastwood described capturing the encounter as a once in a lifetime experience.

"I never thought I would see a dog and a dolphin swimming together in a lake, definitely made my 2019 and will remember it for a lifetime," she said.

Adelaide dolphin expert Mike Bossley was not surprised to hear about the encounter and said dolphins were very playful animals that often enjoyed the company of different species.

"It's actually reasonably common for dogs to hop in the water and swim in association with dolphins," Dr Bossley said.

"What's probably the more interesting aspect is that there are two mother dolphins and their calves who, on a regular basis, swim from Port Adelaide on the Port River down the coastline and into Patawalonga.

"They spend a day or two there and then head back to Port Adelaide … I doubt that they are particularly fearful of dogs."

Adelaide has a history of playful dolphins

Dr Bossley said Adelaide had a rich history of interesting dolphin encounters, with another curious creature known for its relationship with race horses in the Port River back in the 1980s.

"That happened in 1987, it was a dolphin called Billy … there was a guy who used to train race horses by making them swim behind his boat and the dolphin used to join them, sometimes the dog as well," Dr Bossley said.

"You sometimes see them swimming with seals, and people of course as well."

Dr Bossley said safety concerns for dolphins needed to be recognised as they often made their way from the Port River into the Patawalonga with the potential danger of speedboats in the area.

"One important thing is that the dolphins that go into the Patawalonga from time to time, they are in a bit of a vulnerable position," he said.

"There are motor and speedboat events that occur in there and the fact that they go in there regularly needs to be recognised when events are being planned there."