In the 1990s, the CIA's Office of Advanced Technologies and Programs built Charlie, a remote-controlled robotic fish to surreptitiously collect water samples. According to the CIA Museum, the 61cm long robofish "contains a pressure hull, ballast system, and communications system in the body and a propulsion system in the tail. It is controlled by a wireless line-of-sight radio handset." What was the nature of Charlie's missions? That's classified. Seriously. But Charlie is certainly not the only surveillance fish. In IEEE Spectrum, Allison Marsh outlines "the evolution of underwater robots from smart torpedoes to surveillance fish":
In the United States, such research began in earnest in the 1950s, with the U.S. Navy's funding of technology for deep-sea rescue and salvage operations. Other projects looked at sea drones for surveillance and scientific data collection.
Aaron Marburg, a principal electrical and computer engineer who works on UUVs at the University of Washington's Applied Physics Laboratory, notes that the world's oceans are largely off-limits to crewed vessels. "The nature of the oceans is that we can only go there with robots," he told me in a recent Zoom call. To explore those uncharted regions, he said, "we are forced to solve the technical problems and make the robots work."
One of the earliest UUVs happens to sit in the hall outside Marburg's office: the Self-Propelled Underwater Research Vehicle, or SPURV, developed at the applied physics lab beginning in the late '50s. SPURV's original purpose was to gather data on the physical properties of the sea, in particular temperature and sound velocity. Unlike Charlie, with its fishy exterior, SPURV had a utilitarian torpedo shape that was more in line with its mission. Just over 3 meters long, it could dive to 3,600 meters, had a top speed of 2.5 m/s, and operated for 5.5 hours on a battery pack. Data was recorded to magnetic tape and later transferred to a photosensitive paper strip recorder or other computer-compatible media and then plotted using an IBM 1130.
"Meet Catfish Charlie, the CIA's Robotic Spy" (IEEE Spectrum)