Navy attack submarine crashed into an “underwater mountain” at high speed.

What you need to know: In 2005, the USS San Francisco, a U.S. Navy nuclear-powered attack submarine, collided with an unknown underwater mountain at top speed at a depth of 525 feet southeast of Guam. The impact caused significant damage, rupturing the forward ballast tanks and severely damaging the sonar dome.

-Tragically, one sailor lost his life and 98 crew members were injured. Remarkably, the submarine's inner hull and nuclear reactor remained intact, allowing the crew to reach the surface and return to port within 52 hours. An investigation cited navigational errors and outdated maps, leading to disciplinary action against the commander and several crew members.

-The incident highlights the dangers of underwater navigation and the resilience of the submarine crew.

USS San Francisco: The submarine that survived collision with an underwater mountain

We hear a lot about how well-built and state-of-the-art the U.S. Navy's submarines are, and many experts tell us that they are the best on the planet.

In 2005, a U.S. Navy attack submarine was put to the test when it crashed into what many would call an “underwater mountain.”

As crazy as it may sound, the submarine did not sink and was able to return to port. Here's what an expert explained about the incident and his analysis of how the submarine got home.

USS San Francisco (SSN 711): A crazy submarine story

Typically, it is fighter and bomber pilots who have to deal with mountains – especially when flying in poor visibility conditions. Tragically, in January 2022, a South Korean Air Force pilot died after his F-5E fighter jet crashed into a mountain south of Seoul due to poor visibility.

But it’s not just the “flyboys” who have to pay attention to mountains.

In 2021, a US Navy nuclear submarine collided with an “unexplored seamount” – also known as an underwater mountain. The USS Connecticut, a Seawolf-class fast-attack submarine, struck the then-unidentified object in international waters in the South China Sea on October 2, 2021, resulting in moderate to minor injuries to 11 crew members.

This incident was the first involving a U.S. Navy submarine since the USS San Francisco (SSN 711) also struck an unidentified seamount in 2005, unfortunately resulting in numerous injuries and one fatality among the crew. Such collisions are rare but unlikely to be completely avoidable, as researchers estimate there are more than 100,000 seamounts that rise more than 1,000 meters (about 3,300 feet) above the ocean floor (source: National Oceanic and Atmospheric Administration ( NOAA)).

“New estimates suggest that seamounts collectively account for approximately 28.8 million square kilometers of Earth’s surface,” NOAA said. “This is larger than deserts, tundra or any other land-based global habitat on the planet.”

Collisions can be serious

Although a submarine hitting a mountain is not as bad as a plane hitting a mountain, it is still very serious. In fact, it is remarkable that the damage to the USS Connecticut was not greater. Furthermore, it is virtually a miracle that the USS San Francisco did not suffer catastrophic damage when it reportedly hit the unknown seamount at about 30 miles per hour and at a depth of 525 feet.

This incident occurred on January 8, 2005, approximately 675 km (364 nautical miles, 420 statute miles) southeast of Guam while the submarine was traveling at top speed. The resulting collision was so severe that the ship suffered significant damage and there were difficulties maintaining positive buoyancy on the surface after the forward ballast tanks ruptured while the sonar dome was severely damaged. A total of 98 crew members were injured, suffering broken bones, lacerations and back injuries. The 24-year-old Machinist's Mate Second Class from Akron, Ohio, died the following day from head injuries.

Fortunately, the inner hull was not breached and, more importantly, there was no damage to the boat's nuclear reactor. In fact, thanks to the efforts of the command staff and crew, the USS San Francisco was able to surface and was escorted back to port under the escort of the USCGC Galveston Island (WPB 1349), USNS GYSGT Fred W. Stockham (T-AK-). 3017) and USNS Kiska (T-AE-35), while MH-60S Knighthawk helicopters and a P-3 Orion provided further assistance. It took the submarine about 52 hours to reach Guam as it was only traveling at 10 mph.

Temporary repairs were carried out in Guam before the ship was sent to Pearl Harbor for a more extensive renovation. Since the USS Honolulu was scheduled to be decommissioned in 2007, while the USS San Francisco was scheduled to remain in service until at least 2017, the U.S. Navy opted to take over the nose of the former boat and give the latter a much-needed “makeover.” “

The USS San Francisco finally returned to service in April 2009.

Sailors blamed, others honored

An investigation determined that Commander Kevin Mooney, San Francisco's commanding officer (CO), was responsible for the incident – citing poor judgment that led to the collision. A Navy investigation also found that the boat's crew did not use the most up-to-date charts to plan a course.

The U.S. Navy relieved Mooney of his command and also issued him a letter of reprimand. However, he was not accused of any crime nor was he court-martialed. In addition, six crew members were found guilty of endangering a ship and dereliction of duty in their own out-of-court sentencing hearings (“Captain's Mast”). They were demoted in rank and received punitive letters of reprimand.

More importantly, 20 additional officers and sailors received awards for their actions in the crisis, including letters of commendation, the Navy and Marine Corps Achievement Medal, the Navy and Marine Corps Commendation Medal and the Meritorious Service Medal.

“Although the underlying incident compelled me to punish him and relieve him of command, in my opinion this does not mean that he negates 19 years of exemplary service,” Vice Adm. Jonathan W. Greenert, commander of the U.S. 7th Fleet, wrote in his report.

“Prior to the grounding incident, USS San Francisco demonstrated a trend of continuous improvement and established an impressive track record under Mooney's leadership. “In addition, the crew’s post-grounding response under his direct leadership was commendable and enabled the submarine’s recovery and safe return to port.”

Expert biography

Peter Suciu is a Michigan-based author who has contributed to more than four dozen magazines, newspapers, and websites with over 3,000 published articles over his twenty-year career as a journalist. He writes regularly about military hardware, firearms history, cybersecurity and international affairs. Peter is also a writer for Forbes.

All images are Creative Commons.