The mystery of Dunedin's aquatic visitor has been solved.

A dolphin raised eyes and cellphone cameras by swimming around the Andersons Bay Inlet this morning.

After seeing a video of the creature this afternoon, University of Otago Professor Liz Slooten identified it as a bottlenose dolphin.

"It looks like it's very involved in something, possibly feeding.''

Bottlenose regularly visit Dunedin, but were "far more common in groups'', she said.

Either it became separated from its pod, or it could be a rare case in which bottlenose dolphins travelled solo and instead interact with humans, Prof Slooten said.

"Around the world at any one time there are half a dozen or so of these individual dolphins that will befriend people.''

They were known to travel to Dunedin from as far away as Stewart Island, she said.

"That's a much further distance than a Hector's, for example.''

Initially, the identity of the mammal baffled both staff of the Department of Conservation and Monarch Cruises, as they could not get close enough.

Monarch Cruises owner Neil Harraway at one point thought it was a dusky dolphin.

He said he spotted the creature at the same location where a dusky dolphin swam around with its calf a couple of years ago.

However, the dolphin was then identified by someone on board the ship as a bottlenose, which they did not often see alone in the harbour, Mr Harraway said.

jono.edwards@odt.co.nz