A "slumboat" barge, which rented rooms by the night through Airbnb, was like a "bonfire waiting for a match", a fire safety expert has said.
Cabins on the converted coal barge, moored on the River Thames at Hurst Park, East Molesey, cost £29 a night.
But a fire protection specialist who spent a night on board said it was not sufficiently fire-proofed.
Owner Alistair Trotman said there were many fire safety features on board.
Online home rental service Airbnb, which allows property owners to hire out rooms, removed the listing and launched an investigation after it learned of the findings.
Arnold Tarling, a chartered surveyor and member of the association for specialist fire protection, secretly filmed inside the boat during his stay.
"I'd describe it as a bonfire, basically it's timber with loads of holes waiting for a match," he said.
"There is no fire stopping from one end to the other.
"Every single wall, every single door is made out of OSB (processed wood boarding) or ply."
When informed about the concerns, Mr Trotman said the boat had "fire alarms, fire exits, CO2 alarms, fire blankets and fire extinguishers" and other safety measures on board, and was non-smoking throughout.
He said a new escape ladder had been permanently fitted to a fire exit following Mr Tarling's inspection.
Peter Parker, chairman of the Hampton and Molesey Riverside Trust, said residents refer to the vessel as a slumboat.
"It just turned up, an antiquated, dilapidated, floating dosshouse, which contains 10 bedrooms apparently.
"We call it a slumboat because of the conditions on board," he said.
Elmbridge Borough Council said it understood the vessel was being used as a guest house, and no complaints had been received from any guests.
If one were received, it said, it would be looked into.