In 2024, the US military sank the 360-foot Monarch Countess weighing 2,743 tons; the retired vessel now rises 100 feet from the seafloor in 180 feet of water

Visualise a vessel approximately the length of a football field (including the end zones) resting upright on the ocean floor of the Gulf of Mexico, its hull cracked open by the detonation that sank it, with fish now swimming through the openings where cargo would once have been stored. The 360-foot roll-on/roll-off ship known as the Monarch Countess has been retired and given a second life. As of 2024, the 2,743-ton vessel has been added to the thousands of artificial reef sites monitored by Florida, according to the Florida Fish and Wildlife Conservation Commission.

A B-2 stealth bomber took part in the QUICKSINK demonstration, conducted as part of the broader RIMPAC 2024 maritime exercise, to show a low-cost aerial approach to defeating surface vessels, as per the U.S. Air Force. The Countess was sunk during that single demonstration in the Gulf of Mexico. However, the Countess was approved for artificial reef status under the county’s artificial reef plan back in 2023. The Countess was therefore both a military testing ground and a tourist destination.

Deep water, big profile


The Countess rests upright within 180 feet of water off the coast of Destin-Fort Walton Beach. The 100 feet of "relief" the ship provides is one of several metrics reef managers monitor, according to Get The Coast. Florida’s Artificial Reefs vary between 1-511 ft deep, averaging 68 ft. The Countess, however, is much deeper than most sites within the state, per the FWC.

Deliberately sinking objects to create habitat is a booming industry in Florida. As of March 2026, there were an estimated 4,523 artificial reef deployment sites across the state. These are spread across 34 out of 35 of Florida’s coastal counties, the commission notes. They’re fairly evenly shared between state and federal waters. The same database provides a tonnage stat, indicating the dry weight of the reef material used at each site.

Do fish even care?

Scientists have studied this issue. A 2020 study titled “Meta-Analysis Reveals Artificial Reefs Can Be Effective Tools for Fish Community Enhancement but Are Not One-Size-Fits-All,” published in the journal Frontiers in Marine Science, showed that after analysing 39 studies, artificial reefs provided fish density, biomass, species richness and diversity similar to natural reefs.

However, the study found these results varied depending on the geographical location and material used. They concluded, “Artificial reefs are not a ‘one size fits all’ solution to enhancing habitats.” The study also points out that there has been a long debate around whether artificial reefs act like natural reefs. In short, a sunken ship can provide a good habitat for fish, but location and material matter.

The fine print

As time passes, the reef materials can shift, erode, and submerge, particularly if the material is fragile or light, such as metal. Many sites within the database are based on historical data and may not have been confirmed since deployment, the FWC says. The Countess provides a perfect example of how different parties can benefit from one pile of steel.

In the two years since its deployment, the ship has settled into its role as a reef structure, delivering military testing value, local tourism appeal, and a real-world test case for fish habitat formation. Whether it draws the fishing and diving crowds it was expected to continues to depend on how the structure holds up over time. The cargo ship that never dreamed of becoming a celebrity in retirement has been resting 180 feet below the surface since 2024, while the fish go on forming their verdict.