A dolphin is being monitored by a marine rescue charity after it swam miles up a Welsh river and into English waters.
Marine experts think the common dolphin, which is usually more at home in the deep seawater of the Bay of Biscay, must have been chasing fish up the River Dee in North Wales.
The disorientated creature was first spotted by the public in Connah's Quay docks in Flintshire, North Wales, on Monday but then swam further up river to Saltney, near Chester, in Cheshire.
It carried on up the river and was most recently seen near Chester Racecourse.
Locals have been tweeting pictures of the mammal jumping and flipping out of the water.
Stephen Marsh, operations manager at the charity British Divers Marine Life Rescue, said they are keeping a close eye on the dolphin in case it gets stranded on a sandbank.
Mr Marsh said the creature started heading back out to sea yesterday but today it had returned to Chester.
He said: "It's probably been chasing fish in from the sea and then got caught up in the tidal system."
He said tides at this time of year can be both very high and very low and that is probably confusing the dolphin, which is more used to much deeper water.
Mr Marsh said such an event is quite rare, adding that they would step in to take it back out to sea if it does get into trouble.
However, he said it looks healthy and they hope it will find its own way out.
A member of Environment Agency staff doing maintenance work on the River Dee spotted the dolphin around Sealand Road in Chester yesterday and took a photograph as it jumped out of the water.
An Environment Agency spokesman said: "It's likely that the dolphin entered the River Dee searching for food.
"Our rivers are the healthiest that they have been for over 20 years. Because of this we've seen an increase in the numbers of wildlife including otters and salmon returning to our waters."