Afloat in a gray, inflatable dinghy, US Navy sailors scan the surf, awaiting the return of their crewmember. After a few minutes, a slick gray snout pokes through the water as the mammal whistles hello and pokes a signifier—a ball, bell, or other small object—alerting the team of a suspicious discovery. The trainers then hand over a plastic buoy, and the their colleague—a dolphin—flashes its curved tail before disappearing into the murky water. After the dolphin attaches the buoy to the find, he gobbles silvery fish and revels in the trainers’ congratulatory pats. Behind him, a buoy bobs just above the waves, marking the way for Navy divers as they swim down to retrieve the mine or other danger this oceanic watchdog just sniffed out.
The US Navy employs highly trained dolphins—with names like K-Dog, Kahili, and Makai—across the force, including at its bicoastal nuclear submarine bases. At King’s Bay Naval Submarine Base in Georgia and at Naval Base Kitsap in the cold seas near Seattle, marine mammals use their diving expertise and incredible sonar abilities to help the US Navy protect roughly one-quarter of the US nuclear arsenal. From facilitating mine clearance to conducting undersea surveillance, trained marine mammals aid homeland security missions and foreign operations for the US military—and the militaries of its adversaries.
The Navy began training dolphins and other marine life for military missions in 1959. By the 1980’s, more than 100 dolphins lived in Naval facilities, and the program boasted a budget of over $8 million dollars. Under the guidance of specialized trainers, sea lions with grabber devices learned to retrieve mines from the sea floor. Beluga whales practiced patrolling the waters in search of enemy threats. Dolphins studied how to surveil with mouth-held cameras, deliver tools (and even mail) to astronauts training underwater, and trap enemy divers in immobilizing leg cuffs that drag them to the surface.
Today, about 85 bottlenose dolphins and fewer California sea lions live and train at the Marine Mammal Training Program in San Diego. During the day, they study in watery “classrooms,” and at night they swim and socialize in larger enclosures. The Navy uses a reward-based training approach. Dolphins roll over for friendly belly rubs after diving deep into the water. Sea lions wolf down tasty, slimy fish after saluting on command.
In earlier iterations of the program, sharks, rays, turtles, and birds all learned—or at least tried to learn—tasks for the military’s oceanic operations. But not all animals excel at the training. A sea lion named Hercules, for example, failed out when, despite all his training, he simply refused to take any more deep dives. The Navy sold Hercules to SeaWorld, where he was retrained to perform in shows for audiences of delighted children.
The Navy has sound reasons for primarily training dolphins. These mammals evolved to be able to precisely map their underwater environment, including in murky, shallow, and turbulent waters where manmade technology struggles. Dolphins “see” their environment through echolocation—transmitting sound waves and interpretating the “echoes” as they bounce off underwater objects.
Dolphins don’t speak with their mouths but instead emit “clicking” noises by pushing air through “phonic lips” connected to their nasal passages. The sounds are then focused through their fatty, rounded foreheads (aptly called “melons”). This process creates sounds with different frequencies and wave forms, allowing the cetaceans to gather detailed information about their surroundings and search the seafloor for threats like mines, booby traps, and enemy divers. With their stupendous sonar, dolphins can tell a round object from a square one and a hollow object from a solid one. They best the most sophisticated manmade sonar in distinguishing between similarly shaped natural and manmade objects. Purpoises are also enlisted for their abilities to repeatedly dive deeper than their human counterparts and even sophisticated drones.
The Navy’s cetacean companions have displayed their valuable skills on deployments abroad. Five dolphins protected US sailors in Cam Ranh Bay in the Vietnam War; six dolphins escorted Kuwaiti oil tankers through the Persian Gulf in the late 1980s; and nine were assigned in March 2003 to clear Iraq’s Umm Qasr harbor. The dolphins helped US-led coalition forces neutralize more than 100 threats and re-open Umm Qasr to shipping traffic just one week after the Iraq War began.
US dolphins also participate in international military exercises, like the 2018 Rim of the Pacific exercise involving more than 1,000 soldiers and sailors from as far away as the Netherlands and New Zealand.
Other countries enlist their own military dolphins. A 2020 US Naval Institute report made waves when it suggested North Korea’s military could be training dolphins. Satellite imagery revealed pens appropriately sized for dolphin training near a major Naval base on the Taedong River, although the pens may simply have been for fish farming.
During the Cold War, the Soviet Union recruited circus handlers to train dolphins and other marine life for harbor protection. Wearing special spiked muzzles or harnesses with harpoons, the Soviet dolphins could reportedly even kill intruders. But over time, the program’s funding dwindled, and the dolphins were reassigned to perform for tourists. Iran bought the animals in 2000.
Today, the Russian military has most likely revitalized its marine mammal program. Russian forces in Crimea seized Ukraine’s military dolphins during the 2014 annexation. Russia purchased five more dolphins just two years later. (It is unknown whether the animals are supporting the Russian naval forces currently attacking Ukraine.)
In 2019, fishermen in Norway spotted a beluga equipped with a harness for Go-Pro cameras. The harness sported clips embossed with the words “Equipment of St. Petersburg.” Scientists found the situation fishy, suspecting the whale was part of the Russian Navy’s marine mammal training program. After all, the beluga was so familiar with humans that it happily played fetch with Norwegian locals.
Although these stories may sound like science fiction, the US Navy’s work with military marine mammals has generated more than 1,200 scientific publications. Yet the Navy emphasizes the animals aren’t just subjects—they’re teammates. The dolphins, who work untethered in the open ocean, appear to agree. They could swim away if they wanted, but with important work to do and buckets of herring and mackeral waiting at home, these marine servicemembers swim right back.
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