DULUTH — The shipping season opened Thursday in the Port of Duluth-Superior with the American Mariner, which had been wintering here, shifting to the CN iron ore docks to pick up a load and the empty Lee A. Tregurtha passing beneath the Aerial Lift Bridge en route to Marquette, Mich..

The Soo Locks, the connector between Lake Superior and Lake Huron, open Saturday. And though Lake Superior has just 5% ice coverage this year, the U.S. Coast Guard cutter Spar and local tugboat operators have been cutting tracks through the harbor and tending to local slips and docks.

Deb DeLuca, executive director of the Duluth Seaway Port Authority, likened the first bits of activity on the lake to the start of the Major League Baseball season during a press conference at the organization's headquarters earlier this week.

"That's always exciting to see the raw materials, the materials of our every day life, moving through the port," she said.

DeLuca said she is expecting a "full-throttle start" to the season that will include a monthly contract with Spliethoff steamship line for both container shipping and general cargo, the continuation of cruise ships passing through the harbor, and the addition of 55,000 square-feet of warehouse space at the port authority.

Iron ore will remain "king cargo," she said, and grain shipments, which were at a historic low last year, are unpredictable.

Container shipping returned to this westernmost inland port last summer when 200 containers of kidney beans were loaded onto an ocean-going vessel for the first time in decades. With Spliethoff, the ships will move raw materials, semi-finished and finished goods, and machinery between the Twin Ports and Antwerp-Bruges in Belgium. It was the first time in the modern shipping era that there was a monthly liner service between Duluth and Europe, according to Jayson Hron, communications director at the Port Authority.

"Having that regular service means that companies can know that they have a committed route in and out of this area every month," said DeLuca. "For most companies, they need that reliability, that predictability."

Viking cruise line offered Great Lakes voyages last summer, with 400-passenger ships docking in the harbor and delivering day-tourists to shore via tender vessels. This season, some cruises will start or end here — including a tour that starts in Toronto and another that ends in Ushuaia, on the tip of Argentina. With the badly eroded seawall behind the Duluth Entertainment Convention Center still unable to support traffic, some passengers will load at the industrial dock in the harbor.

The port authority is building additional warehouse space, bringing its total to 500,000 square feet, that will open in the latter half of the year. The current storage facility, which serves cargo via railroad, truck and ship, is always full.

"That warehousing component is really a vital component to the entire operation of a multimodal hub," Hron said. "We can't handle all the goods and materials to get them on those transportation modals without [having] that warehousing space."

Coal, the port's second largest export, has dropped in recent years as it's replaced by greener energy sources, and the future of grain remains contingent on factors including the cost of moving wheat out of Midwest markets. But Duluth's General Mills Grain Elevator A, purchased in 2022 by Omaha-based grain merchant Hansen-Mueller, is active again for the first time since 2015.

DeLuca said the port had its best iron ore float for a January in at least 20 years, and she expects that momentum to carry into this season. Kristen Vake, executive director of the Iron Mining Association, said miners have been productive this past winter and are ready for a good season.

Last month, officials with Cleveland-Cliffs confirmed it would be calling back workers to Silver Bay-based Northshore Mining in April — nearly a year after it shut down and laid off hundreds of employees.

"All of our operations will be up and running," Vake said. "This is a really big deal, not only to the miners themselves, but to the folks who work in the communities that rely on mining and the vendor and supplier businesses that support the mining industry."