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.
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