The area where the machine currently sits, stuck, was once under water. The object blocking Bertha’s path may be a remnant of Seattle’s industrial roots, Lorraine McConaghy, a historian with Seattle’s Museum of History and Industry said. The mid-1800s saw the construction of a major steam-powered sawmill in the area, and open water surrounding the mill was a dumping ground.

“It could be just about any industrial artifact you can imagine that might have ended up in the water,” McConaghy said, adding the possibilities included a locomotive or boilers and engines used in the old mill.

Laura Harper, a history teacher from Yakima, Wash., echoed the theory.

“I’m assuming there’s probably an underground building, a ship, some sort of artifact from maybe 100 or 200 years ago,” she said.