How Dolphins and Sea Lions Became Secret Weapons of the Cold War

Most Americans have heard of the U.S. Navy SEALs, the elite special ops force inspired by World War II–era demolition teams and formed during the Cold War. But how many know that in that same timeframe the Navy was training actual marine mammals—including bottlenose dolphins, California sea lions and beluga whales—to handle everything from recovering gear to more hazardous duties like protecting forces and detecting mines?

Though it reads like something out of a sci-fi novel, the Navy Marine Mammal Program (NMMP) has been training service mammals for just such missions since 1963—a year after the founding of the legendary human SEALs.

In 1960, Navy researchers acquired a Pacific white-sided dolphin—not to train it, but to study the hydrodynamic efficiency of its streamlined body and apply their findings toward the design of torpedoes and submarines. That research prompted the launch of the NMMP, which initially focused on the remarkable physiological traits that make certain marine mammals uniquely suited for underwater missions.

“Millions of years of evolution have given these animals exceptional skills and detection capabilities that cannot be replaced by any technology we have today,” said Drew Walter, deputy assistant secretary of defense for nuclear, chemical and biological matters in a 2024 interview.

Dolphins and whales, for instance, possess finely tuned echolocation (biological sonar) that allows them to detect submerged objects with astounding accuracy. Just as impressive, some species can dive well beyond the limits of human divers without suffering from decompression sickness (aka “the bends”)—a crippling and sometimes lethal condition where nitrogen bubbles expand within the bloodstream of an ascending diver.

Each species boasts its own superpowers. California sea lions can stay underwater for up to 10 minutes and reach depths approaching 1,000 feet. Bottlenose dolphins can dive even deeper and remain submerged minutes longer. Beluga whales routinely dive below 2,000 feet and can remain underwater nearly half an hour—but they were phased out of the program due to the operational limitations posed by their Arctic habitats. In the program’s early years the Navy tested the sensory and physical capabilities of a wide range of aquatic creatures—from sharks to sea turtles to shorebirds. Ultimately, program administrators found that dolphins and sea lions were best suited the Navy’s needs.

In 1967, the program moved to a San Diego facility now known as the Naval Information Warfare Center Pacific (NIWC Pacific), where it remains headquartered. Its work soon expanded to study dolphins’ brain function, sensory organs and vocalizations. Handlers also trained dolphins and sea lions to detect, locate, mark and recover objects such as mines—dolphins using echolocation, sea lions their exceptional directional hearing and low-light vision.

As recently as 2013, a Navy dolphin on a training mission happened across a rare 19th-century Howell torpedo that had been lost off San Diego in 1899. Its recovered fragments are being prepared for display at the U.S. Naval Undersea Museum, in Keyport, Washington. That museum also boasts displays honoring Tuffy the bottlenose dolphin, whom it dubs the program’s “star pupil” for his ability to master complicated tasks. In 1965, the Navy loaned Tuffy to its SEALAB II underwater habitat 200 feet under the ocean off the coast of San Diego, where the dolphin ferried supplies to and from surface supply ships, among other tasks.

Another highly successful application has been the use of bottlenose dolphins for force protection­—specifically, to detect inbound enemy swimmers and vehicles, particularly in rough inshore waters, where poor acoustics often defeat electronic detection devices. “They have this extraordinary ability to find objects amidst all of the noise, seaweed and low-visibility environment,” said Walter. The Navy deployed dolphins for this purpose to Vietnam in 1970–71, the Persian Gulf in 1987–88 (toward the end of the Iran-Iraq War) and the Persian Gulf again in 2003–05 (for the War in Afghanistan and the Iraq War). They also patrolled San Diego Bay in 1996 during the Republican National Convention.

Sea lions, meanwhile, have excelled at recovering test ordnance fired into the ocean. The unarmed objects are fitted with acoustic beacons the animal can detect. The sea lion then returns to the surface to accept a bite plate connected to a recovery device. Finally, it dives down, attaches the device to the ordnance and returns topside for a fishy reward while the object is winched up to the boat.

Despite its decades of success, the NMMP has faced criticism. Opponents argue the mammals face unnatural stressors, confinement and such behavioral control measures as anti-foraging muzzles.

Program officials counter that handlers use muzzles strictly to prevent dolphins from ingesting harmful objects. In fact, they say, food is less motivating than play (handlers often reward dolphins with splashes, tickles and encouragement to frolic). Punishment, they note, only leads to refusal.

Most training, they say, takes place untethered in the open ocean, and only a handful of dolphins have failed to return to their open-mesh enclosures over the years. Supporters argue it’s more humane to keep them in the program than return them to the wild.

According to Navy statistics, the program’s dolphins live about twice as long as their wild counterparts, its sea lions up to three times longer—thanks in large measure to attentive handlers, regular veterinary care and diets based on each species’ natural foods.

“Each animal is teamed with a small crew of professionals devoted to that animal,” says Darian L. Wilson, public affairs director at NIWC Pacific. “A team of more than a dozen veterinarians oversees their medical care, providing everything from semiannual preventative physicals to treatment for acute conditions, as well as their nutrition.” Their care is regulated by federal marine mammal protection and animal welfare laws.

The program’s Cold War origins and clandestine activities have also spawned unsubstantiated rumors. One gained traction in 2005 following Hurricane Katrina, after eight bottlenose dolphins were swept from a damaged holding tank at the Marine Life Oceanarium in Gulfport, Mississippi.

Within hours a self-described “accident investigator” claimed that dozens of Navy dolphins, allegedly wearing harnesses rigged with toxic darts and trained to shoot at underwater terrorists, had escaped into the gulf.

Marine Life Oceanarium President Moby Solangi quickly shut down the tale. “That sounds like something from X-Files,” he told NBC reporter Keith Olbermann. “As a matter of fact, [the Navy] provided us these temporary tanks in which we’re holding these animals until they recover.” The Pentagon also stepped in, clarifying the NMMP has never trained animals to attack divers or plant explosives on ship hulls, due to the risk of misidentification.

Just like the SEALs, the NMMP mammals will likely remain the subjects of such fish tales. Both deserve to be remembered for their actual deeds.