The container ship that caused the deadly collapse of Baltimore's Francis Scott Key Bridge is on its way back to port nearly two months after the disaster.

Dali, a 300 meter (984ft) cargo ship, was refloated at high tide Monday and began slowly moving back to port at a cautious speed of 1mph, guided by several tugboats.

The ship had been grounded at the collapse site for seven weeks after it lost power and crashed into one of the bridge's supporting columns on March 26, killing six construction workers and halting most maritime traffic through Baltimore's busy port.

The 21-strong crew have remained on board the ship since the disaster amid investigations by the National Transportation Safety Board and the FBI.

But a perfect storm of the investigation into the disaster, ongoing ship maintenance duties and visa bureaucracy mean the 22 sailors - who have already spent two months in limbo - must remain on board for the 'foreseeable' future.

The damaged container ship Dali is docked at the Seagirt Marine Terminal on May 20, 2024 in Baltimore, Maryland, two months after it caused the collapse of the Francis Scott Key Bridge 

Authorities have refused to let the crew disembark the freighter since the incident on March 26, which killed six workers on the bridge. Maritime unions have repeatedly asked that the men - 21 Indians and one Sri Lankan - are allowed a speedy return to their families.

The crew's morale is already low after FBI investigators seized their cell phones, leaving the men unable to contact relatives or carry out personal admin like online banking to send money to their families.

The ship appeared to start moving shortly after 6am as crews began maneuvering it out of the wreckage. It started and stopped a few times before slowly backing away from the collapse site.

Tug boats guide the damaged ship back to port on Monday with large amounts of debris still strewn across its bow

Crews work to refloat the Dali in preparation to move the cargo ship at high tide in Baltimore, Monday, May 20, 2024

The ship's crew members haven't been allowed to leave the vessel since the disaster. Officials said they've been busy maintaining the ship and assisting investigators. Of the crew members, 20 are from India and one is Sri Lankan.

Officials have said they will be able to disembark once the Dali is docked in Baltimore.

With the hulking cargo ship removed from the mouth of Baltimore's harbor, a newly opened void appeared in the city's skyline.

The altered waterscape also highlighted the progress made on the cleanup effort as crews have already removed hundreds of tons of mangled steel from the collapse site.

A controlled explosion was carried out last week to bring down several massive parts of the wreckage for removal from the waterway. 

Officials said the Dali would move at about 1mph on the roughly 2.5-mile trip back to port, a fraction of the speed it was traveling when it lost power and brought down the bridge.

Extensive repair work will be carried out on the Dali in Baltimore before it can return to sea

In this aerial view, the damaged container ship Dali is docked at the Seagirt Marine Terminal on May 20, 2024 in Baltimore, Maryland

Pieces of the bridge's steel trusses protruded from the ship's bow, which remained covered in mangled concrete from the collapsed roadway.

Officials have said the Dali will likely remain in the port for a several weeks and undergo temporary repairs before being moved to a shipyard for more substantial repairs.

Crews began preparing the ship to be refloated about 18 hours before it started moving. That process included releasing anchors and pumping out over 1 million gallons of water that were keeping the ship grounded and stable during complex cleanup operations.

Crews conducted a controlled demolition on May 13 to break down the largest remaining span of the collapsed bridge, which was draped across the Dali's bow.

Dive teams also completed inspections of the site to confirm there were no obstructions that would hinder the voyage.

Tugboats escort the container ship Dali after it was refloated in Baltimore, Monday, May 20, 2024

The Dali experienced two electrical blackouts within about 10 hours before leaving the Port of Baltimore on its way to Sri Lanka on March 26

The Dali experienced two electrical blackouts within about 10 hours before leaving the Port of Baltimore on its way to Sri Lanka, according to a preliminary report released last week by the National Transportation Safety Board.

The ship experienced two more blackouts as it was approaching the Key Bridge. Those failures caused it to lose propulsion and veer off course at the exact wrong time.

The FBI also launched a criminal investigation into the circumstances leading up to the crash. 

The bodies of six construction workers have been recovered from the underwater wreckage in recent weeks. All the victims were Latino immigrants who came to the U.S. for job opportunities. They were filling potholes on an overnight shift when the bridge was destroyed.

Officials plan to reopen the port's 50-foot (15-meter) deep draft channel by the end of May. Until then, crews have established a temporary channel that's slightly shallower.