Larger-than-expected coral reefs and 30 possible new species: Uruguay's first high-tech deep-sea expedition reveals surprising life

When they planned the historic expedition in September 2025, the researchers who embarked on the Schmidt Ocean Institute's Falkor (too) did not believe they would observe such a wealth of life in the unexplored depths of Uruguay.

Never-before-seen species, coral formations stretching for hundreds of meters, tropical snails no one expects to see in the temperatures of this region of the Atlantic: this is the first time that samples and footage from benthic communities off the coast of Uruguay have emerged from the sea, and what they reveal is absolutely astonishing.

Discovering the ocean depths of Uruguay

Il Río de la Plata It is the second largest drainage basin in South America: formed by the Uruguay and Paraná rivers, on the border between Argentina and Uruguay, this estuary is considered a river only by virtue of the fact that it carries freshwater. Its appearance, in fact, is that of a gulf overlooking the South Atlantic Ocean. And where the freshwater of the Rio del Plata meets the confluence of the warm and very salty Brazil Current and the cold and nutrient-rich Malvinas Current, the oceanographic conditions peculiar, which favor the development of aimmense biodiversity in a relatively small area.

Thirty-five species of whales and dolphins, 63 species of sharks and rays, and the largest breeding colonies of sea lions and fur seals on the continent live here. Yet, until now, researchers have been unable to just hypothesize what was hidden in the depths of the Uruguayan waters.

Last September, however, the expedition led by Dr. Alvar Carranza of the University of the Republic of Uruguay, has reached the slope of the continental shelf, a steep slope that slopes down to the deep ocean floor, and has benthic communities observed for the first time in the deep waters off the coast of Uruguay.

Scientists expected to find an extensive coral reef, cold springs, and chemosynthetic communities. What they discovered, however, was decidedly exceeded their expectations.

New species and a richer-than-expected coral reef

During the historic expedition, the international team led by Carranza discovered that the coral reefs deep sea off the coast of Uruguay are thriving, and it has been confirmed that they consist mainly of Desmophyllum pertusum, a slow-growing coral recently classified as a vulnerable species. They found reef larger and more populated than expected: one of the largest complexes observed covers an area of ​​1,3 square kilometers, more than 180 football fields:

“We always expect to find the unexpected, but the diversity and complexity of what we found exceeded all our expectations,”

said Carranza, who also participated in the investigation that, in 2010, revealed the existence of these formations.

Using the ROV SuBastian of the Schmidt Ocean Institute, aboard the research vessel Falkor (too), the team observed species typical of temperate waters and subtropical species: marine snails, groupers and various sharks.

The team discovered at least 30 possible new species and documented hundreds of species never before seen in Uruguayan waters, such as glass squid, Dumbo octopus, and tripod fish.

In another location they observed worms of the species Lamellibrachia victori That live on cold vents (areas where chemicals like methane are emitted from the seafloor) grow on coral reef ridges. These two communities, the researchers explain, survive on different energy sources: deep-sea corals rely on microscopic food from the water column, while worms feed on chemical energy from the seafloor.

The team also observed a sea ​​snail of the family of Ovulidae feeding on gorgonian soft coral, a common sight in tropical areas of the ocean: as Carranza explained, finding them at these temperatures was like finding a giraffe in Antarctica.

History and Future: From the Wrecks of War to Ecosystem Restoration

Researchers on the Schmidt Ocean Institute's 100th expedition were also the first to explore the wreck of the ROU Uruguay, a Cannon-class destroyer that served as USS Baron during World War II. The United States transferred her to Uruguay in 1952, which used her for several decades as a patrol and training ship, until her sinking in 1995 for a naval exercise.

The science team spent a full day studying the wreck, which now serves as a coral reef habitat, collecting data useful for better understanding how the wreck has changed over time and for assessing the presence of any contaminants.

The most important task of the expedition, however, was to reveal benthic life of an ocean region that we had never had the opportunity to see, collecting fundamental data for the management of Uruguay's marine resources:

"In just thirty years, we've seen a beautiful, healthy, and thriving reef form: this is a message for all of us. If we give the ocean time to recover, it will recover. If we give it the chance to grow and thrive, life will."

concludes Carranza.

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