When a marine expert was called to say a walrus had been spotted in Pembrokeshire, he thought it was a "spoof".
But Terry Leadbetter, from the Welsh Marine Life Rescue, is very happy to be proved wrong.
The walrus, which is thought to be a three-year-old female, has been spotted most days along the Pembrokeshire coastline since the first sighting a week ago.
She has even been filmed trying to get on a fishing trawler in Tenby harbour, and on board a dinghy.
People have been travelling from across Wales to catch a glimpse of the arctic mammal. They normally inhabit coastal areas from Canada to Greenland.
The RSPCA believes it is the most southerly sighting of the species, which has occasionally been seen in Scotland.
Mr Leadbetter said: "We thought it was a spoof call because we don’t get walruses down here.
“But shortly after that we had another report from somebody sounding quite sensible saying it was definitely a walrus so we went out and sure enough it was.”
They are normally found in the Arctic where they use their tusks to make breathing holes in the ice but was first spotted in Ireland about three weeks ago before moving to Wales.
One theory is that the animal may have fallen asleep on an iceberg that was drifting south.
The sight has attracted hundreds of people to the seaside town now that the travel restrictions with Wales have been lifted to coincide with the Easter school holidays.
The Irish Whale and Dolphin Group said they believed the walrus had travelled more than 250 miles over a six day period, and could swim at speeds of four mph.
Geoff Edmond, RSPCA national wildlife coordinator, said, "This was a landmark for the RSPCA’s wildlife team.
"While we’ve been rescuing animals and responding to welfare calls for almost 200 years, I believe this is our first ever walrus call!"
Members of the public who may spot her on the rocks are being asked to keep their distance and not to approach or spook her.
Dogs are also being asked to be kept on leads when they are in the area of the walrus.
If you spot the Tenby Walrus email your pictures to cathy.owen@mediawales.co.uk.
