With guns bristling, police officers in full tactical gear sweep across the vast deck of a cargo ship and creep up the stairs to the bridge.
Their mission: Take the vessel back from armed intruders.
Twice a month, the Natural Resources Police Tactical Response Team practices its craft. Tuesday morning's exercise was aboard the USNS Gilliland, a 956-foot vessel operated by the Navy Military Sealift Command and tied up at the Clinton Street Marine Terminal.
"Basically it's a high-rise lying on its side, but it's a lot more complicated," said Sgt. Mel Adam, the squad leader, of the vessel. "It's easy to secure a house. It's harder to search and secure a ship with 300,000 square feet of cargo area — and every ship is different."
But some things are the same for his squad members — the danger of an 80-foot plunge into the water wearing nearly 40 pounds of gear; narrow stairwells and tight quarters; and unforgiving steel and concrete surfaces that amplify sound and punish stumbles.
So the officers step carefully and watch out for one another.
"We say, 'Head on a swivel, looking for work,'" Adam counseled his team of seven.
With 45 miles of shoreline and more than 1,100 acres, the port of Baltimore is a security challenge. In 2005, The Baltimore Sun uncovered significant security shortcomings, including inadequate patrols.
Upgrades in surveillance equipment — including cameras — and better-trained personnel led to an "excellent" security assessment from the Coast Guard in each of the past four years.
"Over the last few years, the port of Baltimore has made substantial progress in the area of port security and much of that is due to the outstanding, team-first approach by our federal and state security partners," said Richard Scher, Maryland Port Administration spokesman.
In 2006, Gov. Martin O'Malleyassigned maritime security duties to the Natural Resources Police, which works with the Coast Guard and U.S. Customs Service, among other agencies. Its officers protect the Calvert Cliffs nuclear plant and Calvert County natural gas terminal, among other high-risk locations.
Last year, NRP officers joined their partners in Operation Parasite, boarding and inspecting vessels anchored south of the Bay Bridge to look for stowaways, drugs and other illegal goods. No contraband or stowaways were found.
That effort is expected to continue this year, but in the meantime NRP and Maryland Transportation Authority officers stay sharp by practicing on one of the Navy vessels moored near the Fort McHenry Tunnel. In times of war, the ships would be activated to move cargo within four days.
Gary Ford, the Gilliland's captain, who has participated in anti-piracy exercises around the world, said the kind of knowledge gained onboard and in the port can't be taught in a classroom.
"With the amount of things going on in the world, we need trained professionals to respond," he said.
The NRP tactical team was established about six years ago to conduct rural and maritime search-and-rescue efforts and to carry out security assignments.
Its newest member is its only woman.
Officer Lindsey Markert, 24, of Essex, joined the department in 2009 after deciding a career in design and architecture wasn't for her. She was the only one of four officers who applied for the tactical team last year to pass all the tests.
The daughter of a retired Baltimore County police sergeant and a county police dispatcher, Markert said the training, which includes SWAT school, maritime courses and sharpshooting and physical tests, was "daunting."
She rappelled down a 110-foot water tower, did 60 push-ups in a minute and five pull-ups while wearing a 30-pound vest, and swam 200 meters in full SWAT team gear.
"Gender doesn't matter," she said. "It didn't occur to me until graduation, when I looked around and saw I was the only one with a ponytail."