Savannah, Georgia (CNN) Imagine working in a world the color of Irish coffee, where you cannot see much beyond your hand. Where a constant force pushes you away from your task and upends you if you stay too long. And walking? Jagged pieces of iron and piles of debris await at every turn.

That is the office environment of a U.S. Navy team this summer as it salvages a Civil War ironclad vessel in the Savannah River. The team battles back against the underwater challenges, using years of experience and training. The goal: to retrieve artifacts and larger pieces while getting men out of the water before, as diver Cody Bumpass said, they are "literally flying in the current."

"If you don't know what you are doing, it could be a little scary," said Bumpass, a Navy diver 1st class.

For Virginia-based Mobile Diving and Salvage Unit 2, the recovery of the CSS Georgia, scuttled by its Confederate crew in December 1864, requires a mixture of old-school techniques and the latest in technology.

Reminiscent of intrepid divers in Jules Verne's 1870 classic "Twenty Thousand Leagues Under the Sea," the divers wear large helmets, full body suits and are attached to tethers, called "umbilicals," that carry vital air and communication from the mother ship -- in this case a salvage barge about 40-45 feet above.

When they make a discovery, divers run their gloved fingers around an item and give a description that is relayed to archaeologists assisting in the recovery.

A U.S. Navy diver, after a briefing and gear check, strides into the turbid Savannah River.

Everything is built on safety and trust. Team members rotate jobs, from tending and feeding the "umbilicals" to divers, to handling communications and to supervising the dive team. It's the ultimate form of "I've got your back."

Those on the barge also watch for the massive container vessels that ply the Savannah River. They want divers to be at least 50 feet away from the ships' churning propellers and wake.

"You can actually feel a bit of the suction pull you off (the site)," said Bumpass. "They are huge ships, and they are moving a lot of water. It just comes down to safety."

Conversely, those supporting the divers must trust the underwater workers to give them a real-time feel for what's below and whether they have time or the right conditions to salvage that item.

On one dive, for example, an object found on the river floor was described as looking like a bicycle spoke. It turned out to be some kind of wheel or damper.

Surprises on the river bottom

The CSS Georgia is not really a shipwreck, per se. That's because previous salvage operations, including one shortly after the Civil War's end, removed much of the ironclad. Dredging operations in the late 1960s further scattered the vessel, and the chain anchoring a red channel marker -- or buoy -- constantly shifts items.

That means there can be surprises. A part of the vessel may not be where archaeologists expect it to be, and jumbles of iron complicate the search.

Chief Warrant Officer 3 Jason Potts, the Navy's on-scene commander, said the salvage work can be exhausting. Divers drop items into baskets or rig them to a crane that lifts them to the barge, which floats a few miles east of downtown Savannah, near Old Fort Jackson.

Communication, through a wire bundled in the "umbilicals," is vital.

"We are listening to their respiratory pattern. We may hear a little gurgling in their diving apparatus, indicating water intrusion in their helmet," said Potts. "We know each other well. We are listening to the tone of their voice ... the words they are saying. We are listening to their opinions, we are listening to the factual information. We are listening to every single word they say and every breath they take to make sure they are safe on the bottom."

A recent midday dive, like all such operations, included a rigorous predive protocol. Two divers, one dubbed "green" and the other "red," sat on metal benches under a small awning shielding them from the summer sun. A standby diver who would be sent below if one fell into serious trouble sat between the pair. The third diver hasn't been needed thus far on this mission.

The diving supervisor asked a series of readiness questions, including the status of air and other gauges, and tugged on the divers' gear before they stood up.

"Be safe while you guys are down there," said Senior Chief Navy Diver Steve Askew. "The same for topside."

With that, the divers took a long stride from the edge of the barge and plunged into the water.

"Once you take a step off that ledge, it is go time," said Bumpass.

Divers receive extensive safety training

The $15 million removal of the CSS Georgia, under the direction of the U.S. Army Corps of Engineers, is the first visible sign of a long-anticipated state and federal harbor project. The aim is to deepen the channel to a uniform 47 feet so massive cargo ships can reach Savannah's port from the Atlantic Ocean without relying on the tide.

Mobile Diving and Salvage Unit 2, brought in after six months of archaeological dives by Army Corps contractors, has been in the water since the end of June and should wrap up its work in about three weeks.

The divers in March returned from a six-month combat support deployment that was based in Bahrain. Divers performed ship husbandry and conducted salvage and harbor clearance operations. Its previous salvage operations include the space shuttles Challenger and Columbia, the Minneapolis bridge collapse, USS Cole, Swissair Flight 111 and TWA Flight 800.

Work can be dangerous: Two members of Mobile Diving and Salvage Unit 2 died in February 2013 while training at a pond in Maryland.

Divers are trained to learn the effects of pressure, especially in deeper depths, and have equipment topside to deal with any emergencies, such as arterial gas embolism.

At its home in Virginia, the unit trained extensively for the CSS Georgia project.

Working with an explosive ordnance disposal, or EOD, team from the Navy's Kings Bay base near St. Marys, Georgia, Navy divers were tasked with salvaging the ship's four remaining cannons, artillery rounds, the propeller, engine and other components and the casemate, which is the sloped, armor-coated structure that housed the CSS Georgia's guns.

Artifacts from the Civil War vessel CSS Georgia are moved for further inspection and protection.

The cannons, which include a massive 9-inch Dahlgren and two Brooke rifles, were lifted last month and are undergoing conservation at Texas A&M University.

Dive teams often use scuba gear, meaning they have fins, air tanks and can move pretty nimbly around vessels that are being maintained or salvaged. That's impossible here, given the heavy current and little to no visibility.

"Everyone was excited to see the cannons," said Senior Chief Explosive Ordnance Disposal Technician Richard Bledsoe of Kings Bay's EOD Mobile Unit 6. "Everyone was stoked to be a part of something that's been stuck in the water for 150 years. One day, they will be at a museum they can take their families to see and tell them the story they were part of."

The team took advantage of the USBL, an underwater acoustic positioning system that has helped divers find items.

EOD divers have retrieved more than 130 artillery shells and explosive bolts.

The length of time the guns and shells have been in the water has increased the likelihood that water penetrated fuses and saturated black gunpowder. Still, the EOD and salvage divers treated the cannon as if they might have a round jammed into the barrel to prevent future use and injure those who tried to fire the gun. Archaeologists are not yet certain whether that occurred.

Physical training comes in handy when it comes to lifting artillery projectiles that weigh between 65 and 90 pounds.

Divers found about 60 rounds for the Dahlgren gun, but they were considered less potentially hazardous because a flame is required to light the fuse. The Brooke rounds, shaped like a bullet, were more problematic because they are "impact sensitive." In other words: Don't drop them.

"They knew to carry them in a nose-up attitude," said Bledsoe.

'No Confederate ghosts'

Every sunken vessel has a story, and that of the CSS Georgia includes some mysteries.

Researchers have no blueprints or proven photos of the Confederate ironclad, and they aren't sure how it was put together or even its size.

The ironclad was underpowered and not able to engage in maneuvers against enemy warships. So it became part of the city's formidable defenses, which included obstructions and torpedoes, or floating mines. The CSS Georgia, in essence, was a stationary, floating gun battery, with as many as 10 large guns.

It never, however, had an opportunity to fire in anger. It was sunk by its own crew so it would not fall into the hands of Union troops that would soon take Savannah.

There was no loss of life. "There are no Confederate ghosts with us," quipped Lt. Liza Dougherty, public affairs officer for Virginia-based Explosive Ordnance Disposal Group Two. Dougherty's duties have included posting real-time social media updates on the project.

Officials do know that a businessman, shortly after the Civil War, contracted with the U.S. government to salvage the wreck as part of an effort to clear the shipping channel.

Photos: Artifacts, cannon retrieved from Civil War ironclad Photos: Artifacts, cannon retrieved from Civil War ironclad This cannon that was on a Confederate ironclad in Savannah, Georgia, was above the surface for the first time in 150 years on Tuesday, July 21, 2015. It was being raised along with other artifacts as part of a channel deepening project. Hide Caption 1 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad Navy Diver 1st Class Spencer Puett prepares to dive as part of the CSS Georgia salvage operations. About 40 Navy personnel are taking part in the summer salvage operation. Divers have to deal with extremely low visibility. Hide Caption 2 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad The first of four cannons to be removed from the CSS Georgia by U.S. Navy divers is lifted to a barge in the Savannah River on July 15. Hide Caption 3 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad This small cannon, known as a "six pounder," was probably placed at the top of the deck of the CSS Georgia. It would have been used to fire on small row boats sent into Savannah by Federal commanders. It never got a chance to fire on the enemy. Click through to see more fascinating items that have been retrieved. Hide Caption 4 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad This piece of nautical tackle was used to move objects topside on the Confederate ironclad. Teredo shipworms have consumed most of the vessel's wooden hull and components. Hide Caption 5 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad Parker Brooks, a conservator and graduate student at Texas A&M University, studies an elevator screw and firing mechanism from a CSS Georgia cannon. Hide Caption 6 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad A glass top from what archaeologists believe was a condiment bottle. Hide Caption 7 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad After seven months of dives, the wreckage of the CSS Georgia in the Savannah River has yielded 1,500 items, along with cannons and artillery rounds. This pair of leg irons used to hold a prisoner will undergo conservation at Texas A&M University for eventual display. Hide Caption 8 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad The Confederate vessel actually had armor made of inverted pieces of railroad iron because of the scarcity of preferred rolled plate. This schematic shows one of the CSS Georgia's guns -- four of which will be recovered this summer -- and the gun carriage that held it. The next two photos provide details of the highlighted items that have been brought to the surface by hand. Hide Caption 9 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad This piece of iron had eyes, or holes, that were used as part of the rope and wood assembly that allowed the ironclad's crew to move guns closer or farther from portholes and into firing position. The CSS Georgia was scuttled when Savannah fell to Federal forces in December 1864. Hide Caption 10 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad This trunnion cap, which helped connect a piece of artillery to a gun carriage, is in pretty good shape. It's well-known that the South had difficulty in matching technology of Northern equipment during the Civil War. Whereas a Northern version of this piece would have slots, the maker of this Confederate vessel resorted to large holes. Hide Caption 11 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad One of the two leg irons recovered from the CSS Georgia site. "Part of the iron is solid; some has eroded completely," said Jim Jobling of Texas A&M. Scientists will remove encrusted material and inject epoxy into the areas of deterioration. An exact replica will be made. Then the epoxy will be removed from the original item. Hide Caption 12 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad An X-ray of the pair of leg irons showed some areas of corrosion and a good amount of integrity inside. Hide Caption 13 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad The CSS Georgia's wooden lower hull apparently is no longer in existence. But there is some surviving wood among pieces of iron and brass. "The wood is very badly eaten and is more like sponge. As far as conservation, it is not worth doing," said Jobling. "It's too far gone." Hide Caption 14 of 15 Photos: Artifacts, cannon retrieved from Civil War ironclad One of the enduring mysteries of the CSS Georgia is the whereabouts of the only known photo of the ironclad. A gentlemen in the foreground gazes at the vessel in the background. Someone took a photo of the grainy photo at a yard sale in southern Georgia a couple decades ago. Now officials are asking the public in helping them find the original photo . Researchers hope that one day public outreach such as this effort might lead to a diary or something else that could help tell the story of the crew. Hide Caption 15 of 15

Jim Jobling, a project manager with Texas A&M University's Conservation Research Laboratory, said the absence of fastener bolts and other components in some artifacts is evidence of salvaging.

Records indicate that the businessman, apparently in a dispute with the government over his work and payment, may have dumped portions of the wreck back into the river.

Gordon Watts, a longtime diver and owner of Tidewater Atlantic Research, said experts are hampered because so much of the CSS Georgia was taken in previous salvage operations. Watts is assisting the Army Corps of Engineers on the archaeological side of the operation and sits next to the Navy communications operator on the barge, helping provide direction and feedback to divers.

Watts co-wrote an archaeological evaluation that provides the framework used by all the gee-whiz technology on the barge. Technicians use a map that shows where parts of the CSS Georgia are believed to rest. More than 1,500 artifacts were retrieved by contract divers before the Navy team began lifting the heavier items.

Advanced technology guides dive teams

The barge features air-conditioned pods, where contractors and Navy personnel constantly monitor the sonar, GPS and other equipment.

The sonar system provides a 3-D, real-time image of what the divers are doing. Moving dots on some computer screens show the location of the divers and the I-beam used to lift some items. One of the divers carries a tracking beacon and crew members can follow the divers with an image of the plume made by their bubbles.

Divers are entirely dependent on the directions sent from the barge. "Face your umbilical and back up to your left," may be one command. "We tell them, 'You are almost on it,'" said Watts.

Watts, who first dived the CSS Georgia in the 1980s, said this is the first time all the available technology and electronic mapping have been combined in such a way.

Watts, 70, with experience at the USS Monitor and the CSS Alabama wreck sites, said the CSS Georgia had inadequate power, a limited hull design and a top-heavy casemate made of 24-foot long pieces of railroad iron, rather than preferred rolled plate.

"That produced a much higher and heavier casemate," said Watts. The local builders and Confederate navy wanted to get the vessel into the water as quickly as possible and cutting the railroad iron would have been time-consuming.

Jobling said they are confident there is enough casemate left to show a sloped side, corner and gun port for museum display.

It takes time and patience to find all the pieces that remain.

Archaeologists and the Navy were surprised so much timber remained with the iron rails making up the casemate. They tried a couple of approaches before fashioning a device resembling a guillotine to cut through the armor and wood. Sections weighing about 10,000 pounds are then lifted to the surface.

The outer suits the Navy divers wear allow them to walk on the bottom to reach an artifact. Divers carry about 150 pounds of extra weight on their boots, belts and elsewhere to reduce their buoyancy. This time of year the water is mild -- in the low to mid-80s -- and divers typically work in a "slack tide," the window each day when there is little movement in the tidal stream.

Two divers are sent to the bottom at a time, for a dive that often lasts more than an hour. A third diver is on standby, in case there is a medical or other serious problem.

Because of the relatively shallow depth, divers are able to use surface air.

"You don't want to foul your umbilical around yourself or cut yourself," said Watts. "You have to move pretty carefully when you are down there." The added weight makes it impossible for a diver to rise to the surface -- their tenders hoist them slowly up to a ladder on the edge of the barge.

To an observer, it's tempting to look at the helmet (which is mounted with a camera), outer suit and support system and compare such diving to being on the moon.

"In a bizarre way, it is kind of like space because you are in a hostile environment," said Watts. Neither individual would survive without a complex support system. "In space, you can see what you are doing. Here you are blind, and feeling (by hand) with the ability to conceptualize things."

An underwater brotherhood

Bumpass, 31, of Austin, Texas, has a ready smile and a can-do work ethic.

He described how he and Spencer Puett slowly moved part of a hawsepipe, a part of the anchor chain system, across the river floor to the waiting basket.

"I'm pretty sure it's 3,000 pounds, but they said 200," Bumpass said with a laugh.

Diver 1st Class Kurt Eberle, 32, of Racine, Wisconsin, said divers are competitive and want to be on the best team. "Everyone likes to poke fun at each other. It boosts morale, also builds competition and a healthy work ethic."

One example was a line uttered at the dive station when the crew hadn't heard from the divers in a while. "Are they getting their mail down there?"

Six months of dive school whet the appetite for excelling in the unit's tasks, which include ship maintenance and repairs, salvage and force protection. As Watts said, divers know they have to respect the environment in which they work and understand the limitations of their equipment.

"Everyone up there takes this dead seriously," he said.

Eberle said the work requires a well-rounded individual with expertise in many subjects and the ability to roll with the punches.

"It takes hard work and strong desire to be among the Navy's 1,000 divers. Many try. Not that many make it," said Potts.

And, always, there has to be trust.

"Trust in sending that person down below the water line to accomplish the mission," said Potts. "To repair a ship, you consider the fact that we send our divers down to replace 55,000-pound propellers on a submarine, and we send that submarine to sea to go out and support our combatant commanders on that one person's or two people's word that that ship is ready to go. That's an immense amount of trust."