The NSA was once jokingly referred to as No Such Agency because of its penchant for secrecy. The National Reconnaissance Office, founded in 1961, was only declassified in 1992—before that, it didn’t officially exist. To show how much things have changed, today both of those agencies have children’s websites. (As does the FBI, CIA, and DIA.) Not every part of the intelligence community, however, has reached such lofty heights as offering lesson plans for schoolteachers. Here are a few lesser-known arms of United States intelligence:

National Underwater Reconnaissance Office

It took thirteen years for the public to learn about the existence of the National Reconnaissance Office, by way of a short piece in the Washington Post. The National Underwater Reconnaissance Office, on the other hand, remained a secret for twenty-nine years. Where the NRO began as a joint CIA-U.S. Air Force agency, the NURO is the intersection of the CIA and U.S. Navy.

The agency was pivotal during the Cold War, enabling the United States to spy on the Soviet Union using submarines and by tapping undersea communication lines. Its most famous operation (so far) is Project Azorian, in which a ship called the Glomar Explorer was constructed to retrieve a sunken Soviet submarine.

Special Collection Service

Sometimes the Utah Data Center isn’t enough and the NSA needs to get hands-on in foreign countries. To do this, it calls upon the men and women of the Special Collection Service, a joint CIA-NSA signals intelligence agency. The SCS is charged with placing high-tech bugs in impossible locations. To do this, the service can send in Special Collection Elements that are equipped with gear that would make Q jealous—umbrellas that unfold to parabolic antennas, satellite transmitters disguised as simple laptops, and lasers that can read conversations by recording the vibrations of windows.

And they’re not just bugging hotel rooms in Prague. They’re also on the ground in Afghanistan, Iraq, and Pakistan, tapping communications infrastructure and spying on terrorist training camps. As John Pike of the Federation of American Scientists put it, “When you think of NSA, you think satellites. When you think CIA, you think James Bond and microfilm. But you don’t really think of an agency whose sole purpose is to get up real close and use the best technology there is to listen and transmit. That’s SCS.”

Global Response Staff

The Washington Post recently gave attention to a secret arm of the CIA tasked with security operations abroad. The Global Response Staff is made up of hundreds of former members of U.S. special operations forces who often work as contractors. Their mission is to guard spies, but let’s face it: A Delta guy isn’t going to sit around for long. GRS operations have expanded in recent years to include critical security at drone bases, defending Special Collection Elements in the field, and transporting intelligence assets in combat zones. In Benghazi, members of GRS mounted a rescue operation of U.S. diplomats, and later helped evacuate survivors. This is not a job that you take to pad a retirement check. As the Post notes, five of the fourteen CIA employees killed in recent years were from GRS.

Mission Support Activity

In the world of secret operations, the blander the name, the more exciting the mission. A unit with a snooze-fest name like Mission Support Activity—previously the equally boring Intelligence Support Activity—is therefore running some pretty dangerous operations. “Task Force Orange” or “the Activity”, as the ISA is sometimes called, is a highly secret special mission unit charged with intelligence collection for the Joint Special Operations Command. It runs its own spy rings, operates its own Intelligence, Surveillance, and Reconnaissance (ISR) platforms, and generally does whatever is necessary for “operational preparation of the battlefield.”

Hostage Rescue Team

The Hostage Rescue Team is what you join when you’re an FBI agent who loves kitting up and kicking down doors. It is a domestic counter-terrorist unit that operates under the FBI’s Critical Incident Response Group. Its notable missions include security during the Olympic Games, and rescuing guards from rioting prisons in 1991 and 1999. Immediately after the Talledega rescue in 1991, the New York Times reported that the operation began at 3:43. “On a videotape made by the Cable News Network, three or four men dressed in dark clothing and who appeared to be holding rifles scurried across the roof of the cellblock. Seconds later, another boom was heard. Prison officials said the assault was over by 3:46 A.M., and the hostages, all prison or immigration employees, were freed.”

The Hostage Rescue Team was conceived as an FBI variant of Delta Force, with the intention of performing such specialized missions as rescuing hostages from hijacked planes. When it was formally proposed in Washington, however, top officials at the Bureau rejected the plan. The idea of an elite unit was an anathema to the FBI’s core identity, that of Special Agents equally capable in any situation. The proposal interested FBI director William Webster, however, and he and John Simeone, his associate, were soon at Ft. Bragg observing Delta training exercises. As Danny Coulson, founder of the Hostage Rescue Team, wrote in a memoir, Webster and Simeone were taking measure of Delta’s gear when the director noticed something was missing. “I don’t see any handcuffs,” he said, to which a Delta operator replied, “We don’t have handcuffs. It’s not my job to arrest people.” This was a major factor in the FBI embracing the need for its own counter-terrorist team—while the skill set was similar to Delta, the mission required a civilian, criminal justice mindset.