A pod of northern bottlenose whales remain in Scotland's Gare Loch, despite attempts by rescuers to herd the mammals out to sea.
Dozens of boats, many volunteered from the local community, took to the water to try to gently shepherd the whales out of the confines of the loch, which is near Faslane Naval Base, and into open water.
The operation, led by British Divers Marine Life Rescue (BDMLR) and involving the Ministry of Defence and volunteers, succeeded in guiding the whales a significant way down the loch.
However, at the small village of Rhu, the loch narrows significantly and, for whatever reason, the whales decided to turn around and head back up towards the naval base.
BDMLR says the whales may have now split into two groups.
No further intervention attempts will be made today, after what could have been a stressful time for the whales on Thursday.
Northern bottlenose whales are unusual and the rescue team is unsure exactly how they will react to such close human intervention.
Shore-watchers along the loch will now monitor the whales and try to identify individuals using the many photographs taken yesterday.
The Royal Navy says it is offering support as and when needed by the BDMLR team.
It comes as Faslane Naval Base is gearing up for the multinational Exercise Joint Warrior.
Rescuers are keen to move the creatures amid concerns over the impact Joint Warrior, due to start on Sunday, could have on them.
Europe's largest military exercise, it involves warships, aircraft and troops from the UK, NATO and allied forces.
Although Faslane is the hub of operations and 'runs' Joint Warrior, a Royal Navy spokesman explained that only one vessel would be at the naval base for the exercise.
The majority of ships, including HMS Queen Elizabeth, will operate in the far north of Scotland, around the Inner Hebrides, the Minches and this time off the North-East coast.
It will see HMS Queen Elizabeth fly British and American F-35s and operate in a simulated international coalition.
Cover image: The operation to herd the mammals back to sea (Picture: Steve Truluck).