Sightseers at the River Clyde in Scotland were awestruck by the sight of orcas frolicking in the water.

A pod of killer whales was seen from one of the ferries which takes tourists around the estuary of the Scottish river on Saturday.

It was an unusual sight as the mammals usually prefer colder water, and at least one calf was seen with the adult whales by charmed passers-by.

Witnesses described a "once in a lifetime" experience after seeing the whales, which usually feed in Norway and Iceland, up close.

Tourist @OorLorna said on Twitter: "Thank you @Western_Ferries for the fabulous view of the orcas. A once in a life time experience."