Johan Helberg woke up on Thursday morning to find his backyard view of a Norwegian fjord transformed into the side of a giant ship.

An enormous cargo ship, the NCL Salten, had run aground at about 5 a.m. on Thursday, barely missing his house on the shore in Byneset, a part of the city of Trondheim in central Norway.

Mr. Helberg had slept through it all until alerted by a neighbor. ”I was sleeping soundly, deeply, and then I heard a dinging sound, which I wondered might be my doorbell,” he said in an interview on Thursday night. “I thought, who in the world rings the doorbell at 5:45 in the morning? I looked out the window, and he said: ‘Haven’t you seen the ship?’”

The ship was towering over the house, having missed the bedroom by only five or six yards. Had its vector been slightly different, Mr. Helberg said, the ship could have “picked up speed and plowed into the house. It’s completely surreal.”

“I impressed myself by staying cool,” said Mr. Helberg, a retired museum director. “I have seen and been through worse.”

The neighbor, in contrast, had seen the ship come plowing onto land and had been “in shock all day,” Mr. Helberg said — as were many other Norwegians, startled to see photos and videos of a gigantic container vessel wedged onto an unassuming shore.