A blue whale has been caught in video off the coast of Sydney, Australia, in what is thought to be the third local sighting of the world's biggest animal in a century.
The mysterious creatures almost always appear to travel alone and reach sizes of 100ft (30 metres long) in adulthood.
In the clip, the whale, estimated to be 25 metres long, swims beneath the surface of the water at a leisurely pace before breaking through the waves to breathe.
Giving out an eerie groaning sound, the 100-tonne whale ejects a spurt of water before sinking below the waves again.
National Parks and Wildlife Service Project Officer Andrew Marshall told 9News that very little is known about the supersize marine mammals and sightings like this are "valuable".
He said: "Blue whales are largely 'invisible' even to the most avid whale watchers and researchers as the creature is very rarely seen around the world.
"They tend to live very far out to sea, their populations are widely dispersed and we have very limited data on its migration and critical habitat."
Blue whales eat 36,000kg of food every day and their diet mainly consists of krill which are tiny shrimp-like creatures.
The animals are so large their tongues alone can weigh as much as an elephant and their hearts as much as a car, according to onekindplanet.org.
The stunning footage was recorded by Instagram user @seansperception where it was "liked" thousands of times.
In the caption, Sean wrote: "Thought I’d share the video so it’s always there.
"Enjoy this beauty, thanks for all the kind messages and comments."
Animal lovers were thrilled by the footage, with dozens calling the blue whale "amazing" and "beautiful" in the comments below.