Alan Houlihan and his young daughter Muireann were walking along the coast of Valentia Island when she spotted the extremely rare giant mammal.
Mr Houlihan said seeing the creature was “mind-blowing”.
“The size of the thing was astronomical. It was the size of a big bull,” he said.
“He disappeared into the sea for a while and he then came back and put himself on a rock for a good couple of hours. It was fantastic.”
Mr Houlihan said a marine biologist told him the walrus may have fallen asleep on an iceberg and drifted down to the Irish coast.
And Muireann has suggested two possible names for the walrus – Isabelle if it’s a girl, and Cian if it’s a boy.
“She went home last night and she was drawing pictures of walruses. It was so adorable,” added Mr Houlihan.
“We are in lockdown so the kids have gone back to school today for the first time, so it made things a bit easier for them to go back in today with a news story.”
The Irish Whale and Dolphin group (IWDG) estimates the walrus to be a young adult but it is not possible to determine the gender as both males and females have tusks.
The organisation wrote on social media that this was only the third validated sighting of a walrus in Ireland since 1999.
TODO: define component type factbox
It said: “The National Biodiversity Data Centre has 11 walrus records but the Natural History Museum suggest this number may be as high as 20 going back over several centuries. Either way, walrus sightings here are extremely rare.
“Previous walrus sightings validated by IWDG are from April 3, 1999, near Old Head, Clew Bay, Co Mayo, and October 5, 2004, from Mulranny, also in Clew Bay.
“In mid-February, a walrus was photographed off the Danish coast and comparisons of images leave open the possibility that they may be the same individual.
“We would ask members of the public fortunate enough to see it to observe this wayward traveller from a safe distance and to give it the space it requires.”