The bottlenose dolphins have been seen over the past few days in the North Sea close to Bridlington Bay and the town's harbour, and have been swimming only around a mile from the shore.
Flamborough Bird Observatory have been tracking their movements and established they they are from the Moray Firth dolphin population in Scotland.
The University of Aberdeen later confirmed that it is the furthest south animals from the group have ever been recorded.
There are over 130 bottlenose dolphins living in the Moray Firth, near Inverness, and they are the world's most northerly population. They are bigger and fatter than their counterparts elsewhere in the world and have evolved to insulate themselves from the cold North Sea temperatures.
The warm, clear weather during summer 2018 led to record numbers of whale, dolphin and porpoise sightings off the Yorkshire coast.
Humpback whales were seen off Whitby for the first time since 2014 and minke whales were also spotted.
In August whale-watchers aboard a tourist boat in its first season operating out of Whitby were stunned when a minke whale danced and played close to the vessel just five miles from Staithes.
The same month an amateur photographer from Leeds captured these amazing images of porpoises frolicking near the RSPB Bempton Cliffs reserve while he was on a boat trip.