Police said they suspected an explosion in the engine room.
"Nothing indicates sabotage or points to terror," said Trygve Oedegaard, head of operations at the Aalesund police. "But, of course, we have to investigate all options."
Thick black smoke billowed from the stern of the boat, the MS Nordlys, of Norway's Hurtigruten line even before it pulled into the dock at Aalesund, 230 miles (375 kilometres) northwest of the capital of Oslo. Police sealed off parts of the town as the smoke engulfed nearby buildings.
The ship's emergency evacuation began after the fire started at 9 a.m. (0700 GMT), with more than 100 passengers piling into lifeboats in the frigid waters. The rest of the ship's 207 passengers and 55 crew were evacuated at the dock at Aalesund.
Hurtigruten said all the passengers were unharmed but that nine crew members were admitted to Aalesund hospital, two with serious burns and smoke inhalation.
The chief of Aalesund's fire department, Geir Thorsen, described the blaze as "big and intense."
More than 12 hours after the fire began, Thorsen said they were in control of it, but the ship was taking in water and listing. Pumping operations were halted as the ship continued to tilt.
"Our main challenge now is the stability of the ship," Thorsen said. Two units of firefighters specializing in offshore fires were involved in the operation.
Oedegaard said that three rescue workers who pumped water from the ship were lightly injured and treated for inhaling smoke fumes.
Passengers said the cruise ship, which was travelling north from the city of Bergen, had organized an orderly evacuation.
"We were sent up on deck and given our lifevests," Danielle Passebois-Paya, a French tourist, told Norwegian daily Aftenposten. "It took only a few minutes after the alarm and we were in the lifeboats."
"It was a well-organized evacuation," she added. "The crew did a really good job. Everything was calm and went smoothly. There was no panic."
Thorsen could not confirm reports that the ship's fire-extinguishing system did not work, but said its electricity system was knocked out.
"There are no indications that the fire had spread to other rooms in the ship," he said.
The MS Nordlys plies Norway's western coast on the popular 1,500-mile (2,500-kilometre) cruise between the southwestern city of Bergen and the northern town of Kirkenes, high above the Arctic Circle near the Russian border. The route features spectacular fjords, mountains, islands and Arctic wildlife, and carries both tourists eager to see the scenery and locals and cargo from coastal cities and hamlets.
Aalesund, with a population of 42,000, is an Art Nouveau town once voted the prettiest in Norway.