Tourists and local people were treated to a spectacular show when a 30ft sperm whale turned up on the coast off a Scots town.

Fears for the whale's safety in the bay's shallow waters were growing as experts tried to understand why it was far from its usual deep-sea haunts.

Chris Jackson, 54, of Chalice Charters, Benderloch, near Oban, who photographed the whale in Oban Bay, said: "We run whale-watching trips, so I am used to seeing whales, but I have never seen a sperm whale before – it's quite a coup.

"We expect to see minke whales, which are quite prevalent in local Scottish waters. Occasionally, there is a humpback whale, in the Sound of Sleat, or an Orca in the Minch, but a sperm whale in the harbour at Oban is a once-in-a-lifetime thing."

He added: "I posted the photos on Facebook on Saturday night and we have so far got 40,000 hits.

"It's fantastic that people can get so close to a whale and it's great for tourism that we have whales, but I am more concerned now that it gets back to where it should be.

"I don't want it to stay in the harbour."

Mike Robertson, of Oban, said: "I saw it circling for some time in the bay on Saturday, then I saw it breaching, I saw the whole tail come up, it was huge, but I am very concerned that the creature will find itself trapped in the bay.

"A sperm whale lives in the depths of the ocean, so hanging around here is like it being in a paddling pool.

"There have been reports of other whales in the bay over the years, but never anything like this."

David Keys, of the isle of Kerrera, across the bay from Oban, said yesterday: "We have seen it a few times today and we reckon it's around about the 30 ft mark. It seems to be circling."