“He isn’t well and is confused,” police told the TT news agency.
The man was found by a security guard near Skarvik harbour in the city’s Hisingen district around 10am on Sunday morning, according to the Göteborgs-Posten (GP) newspaper.
He was wearing only a light-blue long-sleeved t-shirt, blue jeans, and brown shoes. He had no jacket nor was he carrying any form of identification.
The man, believed to be in his early twenties, was taken to Sahlgrenska University Hospital for care.
But on Sunday night he was still unable to tell authorities who he was or what had happened to him.
“He babbles and can’t explain what happened,” police spokesperson Björ Blixter told TT.
After initial reports about the man surfaced in local media on Sunday, police received a number of tips about who he could be.
“We’re working feverishly to determine his identity and hope that we get some clarity soon,” said Jan Frisk of the Hisingen police district to TT.
A number of people contacted police on Sunday and provided descriptions which seem to match that of the man.
Police suspect he may have been assaulted.
“He has certain injuries, like some on his face, that make us think he was the victim of a crime. But we still don’t know. We haven’t been able to get anything out of him. He isn’t well and is confused,” said Frisk.
According to Sahlgrenska hospital spokesperson Marianne Thulin, the man’s injuries appear to be minor.
Speaking the GP, Blixter said the man was about 180 centimetres tall with short, medium blond hair and brown eyes.
Anyone who may have information about the man can call the police information line at 114 14.