A 689-foot freighter began taking on water Saturday morning after the massive ship hit an underwater obstacle in Lake Superior near Grand Portage, Minnesota, forcing about half of the 22 people on board to evacuate, the U.S. Coast Guard said. 

The Michipicoten, which was carrying taconite, a low-grade iron ore, was around 35 miles southwest of Isle Royale when it began flooding. Isle Royale is part of Michigan.

The Coast Guard said that there was no sign anything spilled into the water from the ship as pumps on board worked to displace the water and reduce the ship’s listing from 15 degrees to 5 degrees. 

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The ship taking on water

A 689-foot freighter ship, right, began taking on water Saturday morning after it hit an underwater obstacle in Lake Superior, forcing about half of the 22 people on board to evacuate, the U.S. Coast Guard said.  (Jeff Leech via Facebook)

The Michipicoten was headed to port for repairs with the bulk carrier Edwin H. Gott alongside it. 

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The ship heading back to shore

The Michipicoten, right, heading to port for repairs with the bulk carrier Edwin H. Gott, left, alongside it.  (Jeff Leech via Facebook)

U.S. Coast Guard, Border Patrol, and National Park Service vessels remain actively involved, the Coast Guard said. 

The cause of the collision is under investigation. 

Lake Superior

Lake Superior is the largest freshwater lake in the world by surface area. (Brian Peterson/Star Tribune via Getty Images)

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The collision occurred in the northwest part of the lake, which straddles the U.S.-Canadian border and is the largest freshwater lake in the world by surface area.

The Associated Press contributed to this report.