A clip showing a tidal surge up a popular Scottish river is 'making waves' online after it was posted by a stunned local.
Dr Henk Pieter Sterk was shocked to catch the incredible moment on camera as he crossed a bridge over the river in the northern Highland town of Thurso last week.
The 30-year-old shared the 45-second clip online, with the video showing a group of large waves charging towards the bridge before passing under it.
Posting it on Twitter, he described it as "incredible", writing that he'd never seen such a tide surge coming up the Thurso river before.
Known as a tidal bore, it is usually formed by the incoming tide forming a wave that rushes up a narrow river going against the current direction of the river.
Speaking about the fascinating clip, Henk Pieter, who is originally from northern province Fryslân, in the Netherlands, moved to Thurso four and a half years ago, he said: "I was out looking for otters in the river.
"Five of them have been seen for the past couple of days and I was fortunate enough to see them almost daily since last week.
"I was surprised, as I'd never seen a tidal bore before in Thurso, nor have a lot of other people according to the responses on Twitter!"
Peatland ACTION project officer with NatureScot added: "It's been amazing to see how the video's taken off, to be honest, normally my tweets don't reach the local community up here because of my research background and peatland-related tweets."
The video has since been viewed over 127,000 times with people flocking to comment on the fascinating natural phenomenon.
One fan of the clip posted: "Maybe you could call it The Thurso Pseudotsunami."
Another wrote: "The power of nature is indeed a humbling sight and puts you in your place in the grand scheme of things.
"Can you imagine what the first hunter-gatherers thought of this when they saw it?"
One person thought it might be a wee visitor from another part of Scotland: "I suppose it's been checked out that Nessie hasn't managed to get in there and is having a wee swim?"
While another quipped: "Watching this is such a bore!"
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