Hundreds of dolphins have been causing "quite a stir" by frolicking and fishing in the North Sea off Scarborough.
The pod of bottlenose dolphins, thought to number 225, is believed to have made its way south from the Moray Firth in Scotland.
Amateur naturalist Fred Tiles, 70, said the pod had come "really close to shore and Marine Drive is filled with people with binoculars and cameras watching them breaching and throwing fish".
Meanwhile, Grant Ellis from The Sea Mammal Research Unit, said: "The population has been increasing in Scotland, so it could be that they're finding new areas of habitat and that the Yorkshire coastline is good for them."
Mr Ellis, a conservation ecologist who has been studying the group, said: "This is one of the largest pods around the UK.
"We've definitely seen them foraging in the area, so we know that they are fishing and they are finding the prey that they need.
"The population that we find here are the largest of their species in the world and it's thought this is because of the cooler waters in the North Sea; they have thicker blubber reserves."
He added: "There's been increased sightings of bottlenose dolphins off the coast of Yorkshire over the past decade or so. We have about 225 in this east coast population in Scotland and we believe they have expanded their range."
Mr Tiles, who set up the Scarborough Dolphins Facebook Group, said: "I saw one throw a huge salmon yesterday."
"I think the richer seas we have here now because of fishing restrictions are responsible for luring this pod down from Scotland. I think that's what's bringing them."
Mr Ellis agreed sea conditions might be behind the dolphins' presence near the famous resort.
"There have been a lot of marine heatwaves going on and it could also be that environmental conditions in Yorkshire are improving - it's something we're investigating."
Mr Ellis said each dolphin could be individually recognised through "unique markings".
"One of the things that we're looking at is which animals are present on the Yorkshire coastline and how they are moving between Scotland and England," he added.
As to whether the huge pod's stay in the area was set to continue, both men agreed the future looked bright for dolphin spotters along Yorkshire's east coast.
Mr Ellis said: "It's really encouraging that they are being seen on a regular basis and in quite large group sizes."
Mr Tiles added: "Five years ago you were lucky if you saw a group of five or six; now it's in the hundreds."
"They're here to stay I think - they'll definitely be back."