On the last day of 1862, about nine months after fighting in a Civil War battle in Hampton Roads, the nation’s first ironclad warship sank off the Outer Banks coast.
The remains of the USS Monitor lay relatively untouched on the ocean floor for more than a century, until officials uncovered it in 1973. Historians and scientists have been studying the wreckage ever since.
A new trove of 3D data and imagery reveals the clearest picture yet of the shipwreck site, allowing officials to examine the exact outline of the abandoned hull and everything on and around it.
It was released over the weekend to coincide with the 164th anniversary of the Battle of Hampton Roads.
The project was a partnership between NOAA and Northrop Grumman, the aerospace and defense contractor. The company used emerging sonar technology last fall to map the Monitor wreck more than 200 feet underwater.
“I was honestly floored, just the sheer resolution of them was astounding,” said Tāne Casserley, a maritime archaeologist with the Monitor National Marine Sanctuary under the National Oceanic and Atmospheric Administration.
“They're really making that history come alive for us in ways we haven't had before.”
During the Civil War, the U.S. Navy built the Monitor in about 100 days in a race to counter the CSS Virginia.
After taking over what’s now the Norfolk Naval Shipyard in 1861, Confederates had salvaged the USS Merrimack from the bottom of the Elizabeth River and turned it into the fearsome ironclad Virginia.
Large, wood-hulled ships at the time moved slowly and couldn’t go too close to land, Casserley said.
The Monitor, designed by a Swedish engineer, “was much smaller, more maneuverable and could go in shallower water,” he said. “For the first time ever, the ship and the guns can move independently. So that's the ancestor of every naval gun today.”
The Monitor made it to Hampton Roads just in time in March 1862. The Confederacy had quickly overtaken two Union ships with the brand-new CSS Virginia.
The Monitor sailed into the Chesapeake Bay harbor shortly afterward and traded shots with the Virginia in what became known as the first “battle of the ironclads.”
“Neither ship was seriously damaged, but the Monitor effectively ended the short reign of terror that the Confederate ironclad had brought to the Union navy,” the National Park Service states on its website.
Later that year, the Monitor was being towed by the USS Rhode Island to help with blockades farther south when it encountered a storm and sank off Cape Hatteras on Dec. 31. Forty-seven crew members were rescued but 16 died.
Officials would not find the wreck until 1973. Two years later, it became the first U.S. national marine sanctuary. These areas are federally protected and managed to conserve natural, cultural and historic resources.
The Mariners’ Museum and Park in Newport News displays hundreds of artifacts recovered from the site, such as silver utensils, glass bottles, sailor clothing and a red lantern, which was the last thing crew members of the Rhode Island reported seeing as the Monitor sank.
Conservators are also in a long-term process to preserve the ship’s engine and turret, which now sits in 90,000 gallons of caustic solution at the museum.
But Casserley said so much more remains hidden underwater.
He’s worked for the Monitor sanctuary since the early 2000s and has dived to the shipwreck almost 80 times. But those in-person observations come with challenges, such as limited time and shifting sediments and ocean currents.
With the new sonar technology, “it's looking at everything in hyper detail, and that's just something I can't do as a scuba diver.”
Northrop Grumman approached NOAA last year and offered to fund and lead the project through its Technology for Conservation initiative, which collaborates with third-party organizations to leverage its “innovative technologies” in places otherwise hard to reach.
It also allows the company to refine its technology, said Justin Zepp, a program manager at Northrop Grumman.
In September, the team deployed an autonomous undersea vehicle to map the site off Cape Hatteras within a few hours, using micro synthetic aperture sonar.
A traditional sonar system would use devices to emit sound waves and wait for them to reflect off the ocean bottom, essentially “sending out a pulse and receiving it back,” Zepp said.
“What we’re doing is we're continuously transmitting, similar to how a dolphin would, and continuously receiving, and we're building up a wider aperture of our receiver.”
That gives the images a much higher resolution, like adding pixels to a computer or TV screen, he said.
Probes attached to the underwater vehicle also collected DNA samples to assess marine life at the site. The project found evidence of several fish and invertebrate species, including pearly razorfish, twospot flounder and cone snails.
Casserley said 3D imagery will help officials add dimensions to storytelling about the Monitor, too.
For example, Northrop Grumman created a video simulating the ship’s final moments and how exactly it fell onto the sea floor.
That can help people imagine the “harrowing” experience for those on board, Casserley said.
“When we talk about the Monitor and we're doing programs with kids, instead of just showing that photograph or drawing, now we can make it come alive.”
You can explore the new imagery and information on the Monitor National Marine Sanctuary’s website.
