The drugs, which have an estimated street value of $4 million, were found on Dec. 18, stuffed in two gym bags hidden in a shipping container from Panama, the Baltimore Sun reported.
"'Tis the season for giving, but sometimes it's better to just seize," the agency said in a release Tuesday.
Steve Sapp, a customs spokesman, said that so far no arrests have been made, but agents are investigating how the drugs came to be placed inside the shipping container and where they were heading.
"Anyone with access to that container from the moment it started getting filled up to the moment we opened it up could have thrown the bags in there," Sapp told the Sun. "In these types of things, it's really hard to get a lead."
This was the largest drug bust made at the port of Baltimore since 2007, when 310 pounds of cocaine was found in three duffel bags inside a refrigerated container from Ecuador.
"When we do see something this big, it tends to be a little alarming, so we'll take a closer look at containers coming in from Panama," Sapp said.