Submarines are engineered to endure the most extreme underwater threats—torpedoes, depth charges, and catastrophic system failures. Some have even been intentionally scuttled. Yet one of the strangest episodes in U.S. Navy history had nothing to do with combat or machinery. It involved a shark barely bigger than a house cat.
Incredibly, this tiny predator inflicted enough damage to force the submarine to abandon its mission and return to port. The bizarre incident became a naval oddity, a striking reminder that even the most advanced warships can be undone by the smallest forces of nature.
The US Navy’s nuclear fleet was affected
This unusual incident occurred within the U.S. Navy’s nuclear fleet, specifically impacting Ohio-class submarines, during the Cold War.
The Ohio-class consists of four guided missile submarines (SSGNs)—the USS Ohio, Michigan, Florida, and Georgia—as well as 14 ballistic missile submarines (SSBNs), including the USS Henry M. Jackson, Alabama, Alaska, Nevada, Tennessee, West Virginia, Kentucky, Pennsylvania, Nebraska, Maryland, Rhode Island, Louisiana, Wyoming, and Maine.
What makes the Ohio-class unique?
Recognized as the largest submarines ever built for the Navy and among the biggest globally, they are second only to the Russian Navy’s Typhoon-class and Borei-class. Notably, the Ohio-class carries a greater payload, with each submarine outfitted with 24 Trident II missiles, exceeding the 16 on the Borei-class and 20 on the Typhoon-class.
Issues with technology started during the Cold War
During the Cold War, submarines stood at the forefront of military innovation, showcasing some of the era’s most advanced technology. Yet life beneath the waves was rarely trouble-free—crews frequently dealt with problems like oil leaks, severed electrical lines, or damaged sonar domes and sound sensors that could fail without warning.
In many cases, these malfunctions were serious enough to force the submarines to cut their deployments short and return to port for essential maintenance.
Cookiecutter shark was the culprit
At first, Navy personnel feared the damage had been caused by a sophisticated Soviet device—a terrifying thought amid Cold War tensions. The truth, however, was far stranger: a cookiecutter shark was to blame.
Nicknamed the cigar shark for its slender, torpedo-like body, this small predator typically measures just 16 to 20 inches and is found in oceans worldwide. Despite its modest size, it has a fearsome feeding technique: it bites circular plugs of flesh from much larger animals using its serrated, saw-like teeth. The precision of these wounds is so exact they resemble cuts made with a cookie cutter—hence the shark’s unusual name.
A dome was added to protect the submarines
Cookiecutter shark bites have been found on a wide variety of sea-life and have even been noted on manmade structures, such as oil rigs, as they attack any soft area that is exposed. The Navy eventually realized the shark was behind the damage to its nuclear submarines and decided the best way to counter it was to place a fiberglass dome around the vessels’ most sensitive parts.