People have been warned to keep their distance from wild dolphins after a woman was photographed swimming with a cow and its calf.
Boat skipper Jonathan Evans witnessed the incident at Ynys Lochtyn off the coast of Cardigan Bay in Ceredigion last month.
He described the woman's behaviour as "selfish" and "unsympathetic".
Ceredigion council said people should enjoy coastal activities but not disturb special wildlife and habitats.
Mr Evans, from Dolphin Spotting Boat Trips, took photographs of the incident before intervening.
He said: "It was a family with two kayaks - a mum, dad, little boy and little girl... they were within feet of the dolphins.
"The mum was in the water and was pursuing the dolphin repeatedly."
He was concerned the young girl was also going to enter the water so shouted over to the kayakers.
"We needed to explain they were in a conservation area and it was against the law to swim with dolphins," he said.
He later reported the incident to the marine protected area officer.
"I have sympathy for the need for people feel to get close to these animals," he said.
"I'm not the person to be lecturing about visiting dolphins when we run a boat trip business but they probably don't know the rules and it's worth going over to them and explaining the rules. "
The Ceredigion Marine Code of Conduct asks water users to stay 100 metres away from dolphins and porpoises encountered at sea.
Under the Conservation of Habitats and Species Regulations 2017 it is an offence to deliberately disturb cetaceans.
A spokeswoman for Sea Watch Foundation urged people not to closely approach bottlenose dolphin.
She said: "While dolphins are charismatic animals, they are also large and powerful predators that have the potential to seriously injure a person.
"Persistent pursuit of dolphins can also lead to long term behavioural changes that can affect the survival of the population as a whole."
Ceredigion council's cabinet member responsible for economy and regeneration Rhodri Evans said: "Cardigan Bay's wildlife is a great asset to the economy of our coastal communities and is also important in its own right.
"It is because of this that we ask residents and visitors to enjoy dolphin and other wildlife sightings at a safe distance.
"Although the temptation to have a close-up view is understandable, we can't risk disturbing Cardigan Bay's wildlife and possibly driving them away. It's the last thing anyone wants."