Submarines are engineered to survive some of the harshest conditions imaginable beneath the ocean’s surface, from enemy torpedoes and depth charges to devastating onboard failures. In some cases, they are even intentionally scuttled during testing or disposal operations. But one of the most unusual incidents in United States Navy history was caused by neither combat nor equipment failure. Instead, the culprit was a shark no bigger than a house cat.
Remarkably, this small creature created enough trouble to force the submarine to abandon its mission and head back to port. The strange event has since earned a lasting place in naval lore, serving as a reminder that even the most sophisticated vessels can be vulnerable to the smallest—and most unexpected—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
Throughout the Cold War, submarines represented the cutting edge of naval technology, pushing the limits of engineering and stealth. Life beneath the waves, however, was far from easy. Crews regularly faced challenges like oil leaks, malfunctioning electrical systems, or damaged sonar domes and sound sensors, any of which could fail without warning.
Often, these technical problems were severe enough to force missions to end prematurely, requiring submarines to return to port for urgent repairs and essential maintenance.
Cookiecutter shark was the culprit
When Navy investigators initially inspected the damage, they suspected it could have been the result of advanced Soviet technology, an alarming possibility during the height of the Cold War. The real explanation, however, proved to be far more unexpected: a cookiecutter shark.
Often called the “cigar shark” because of its slender, torpedo-shaped body, this species typically grows to about 16 to 20 inches in length and is found in oceans worldwide. Although relatively small, it feeds in a remarkably aggressive way. Using its sharp, saw-like teeth, it removes clean, circular plugs of flesh from animals much larger than itself. The round wounds it leaves behind resemble cuts made by a cookie cutter, which is how the shark earned its common 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.