Key West, Florida (CNN) -- They search the ocean depths hunting for evidence left by predators deadlier than great white sharks.
They are members of the FBI's Technical Dive Team, an elite group of special agents tracking terrorism underwater.
Starting next year, this 10-member team could be called on to search for evidence left behind by international terrorists in water contaminated by chemical, biological, radiological or nuclear waste.
"There have been enough scenarios recently," says team member Supervisory Special Agent James Tullbane, citing the 2008 attacks in Mumbai, India, which began when terrorists entered the port city by boat.
"If you look at Mumbai and you look at various international incidents that occurred where there's attacks on American civilians or attacks on American interests where water has been involved, ... we determined that we really do need to expand our capabilities."
A year ago, the FBI created the Technical Dive Team with a primary mission of gathering evidence after a terrorist attack to help find and prosecute those responsible.
The team's ability to operate in contaminated water and to dive at extreme depths sets these divers apart from the FBI's existing Underwater Search and Evidence Response Teams.
A large part of the Technical Dive Team's training is focused on diving in hazardous materials, Tullbane says. Instead of air tanks, the divers use a hose connected to a surface supply system.
"It not only provides the air, it collects the air that you exhale and brings it back to the surface," says Michael Tyms, the team's program manager.
The divers also wear specialized dive suits and old-fashioned hard steel helmets so they can safely operate in contaminated water without being exposed to toxins.
The new equipment also allows the divers to search a crime scene as deep as 300 feet. A safe recreational dive is about 130 feet.
The team, which is halfway through its two-year training program, is scheduled to be fully operational by next year, once all its certifications are complete, Tullbane says. In the meantime, the divers will perform missions they feel they are capable of doing without high risk of injury.
A few weeks ago, the team was called to duty after the U.S. Coast Guard asked the FBI for assistance with a case involving a "narco sub," a semi-submersible vessel regularly used to smuggle drugs.
When the Coast Guard spotted the vessel off the coast of Honduras, its crew sank the watercraft. They were later detained, according to a Coast Guard press release.
"The thought was, 'Hey, somebody could go down and retrieve those narcotics,'" says Tyms. "So they called us and we said, 'Yep that's the type of mission we could do.'"
Armed with their state-of-the-art side sonar and their surface air supply system, the FBI divers headed to the Caribbean and a blighted, contaminated patch of water, ironically close to a prime recreational dive spot, the world's second largest barrier reef.
"Once it sunk, diesel (fuel) was leaking out into the water, into the cargo hold," says Tyms.
In the cargo hold 80 feet below the surface, the divers found nearly 15,000 pounds of cocaine estimated to be worth $180 million in street value, according to the Coast Guard.
The divers went down in pairs. It took eight divers, 15 dives and 24 hours in the water to bring the blocks of tightly packed cocaine to the surface.
The FBI dive team played an "essential" role in locating and recovering the drugs, according to Coast Guard Lt. Cmdr. Peter Niles.
During their mission, the most dangerous threat to the divers didn't come from the hazardous water or the marathon dive session, Tyms says.
"Our memorable moment was when two divers jumped in the water and a shark came out of nowhere and started swimming around them," he says.
The team can only hope that a curious shark remains its most dangerous dive encounter.