In the days following a routine maritime patrol off the coast of Deerfield Beach, Florida, scientists and emergency officials began investigating a series of large sinkholes that formed on the Atlantic seafloor.

A Coast Guard vessel conducting a standard safety sweep encountered a depth reading that did not match nautical charts. The instruments measured roughly 40 feet of water where charts indicated about 12 feet. After resets and repeated checks, the reading remained consistent, prompting an aerial survey. Sonar from a surveillance aircraft confirmed a depression nearly 300 feet across in the ocean floor.

Shortly after, a second collapse was detected closer to Pompano Beach. That sinkhole measured nearly 450 feet across. The collapses created strong currents and unusual water movement near the shoreline. Beachgoers and fishermen observed the water churning in circular patterns as sand and sediment were pulled into the voids.

Authorities responded by closing 47 miles of coastline to the public. Evacuation procedures were initiated in areas near Boca Raton, and Coast Guard vessels enforced exclusion zones offshore. Aerial surveys and satellite imagery were used to map the affected sections of the seafloor.

Geologists investigating the incident pointed to the region’s geological structure. Much of Florida sits on a platform of porous limestone that formed from ancient marine sediments and shells. This rock type dissolves when exposed to slightly acidic water, a process that creates hidden cavities and tunnels over long periods. This landscape is known as karst terrain. When sections of that underground network weaken, the ground above can collapse.

The speed at which the recent collapses appeared drew attention from researchers. While sinkholes are not uncommon in the region, the multiple formations occurring within a short timeframe suggested the underground system may be under stress. Rising sea levels may be a factor, as salt water mixing with freshwater aquifers can accelerate chemical reactions that weaken limestone. Temperature and water pressure fluctuations can also widen cracks and destabilize cavern ceilings.

Several days after the initial collapse, a black, tar-like substance washed ashore near Pompano Beach. Testing ruled out petroleum from ships or drilling platforms. Analysis indicated the material contained ancient organic compounds from deep limestone layers. Carbon dating estimated some of the material formed tens of thousands of years ago, during the last ice age.

Officials also documented effects on marine wildlife. Sea turtles were found coated with the substance, and several arrived at rehabilitation centers with signs of ingestion. Marine biologists monitored dolphins after irregular breathing behavior was observed. Offshore instruments also detected elevated methane readings rising from fractures in the seafloor.

On land, building inspectors reported cracks forming in foundations near Pompano Beach, and evacuation orders were issued for structures showing signs of ground movement. Coastal highways developed stress fractures, and beachfront businesses faced uncertainty as closures continued.

Seismic monitoring stations recorded a series of small tremors along the Atlantic side of Florida. The vibrations were not powerful enough to cause damage, but their pattern drew attention. Some geologists suggested the tremors could be linked to the collapse of underground caverns or water rapidly flooding newly formed cavities.

Researchers also noted that the geological formations beneath Florida’s coast extend beyond the state. Similar layers of porous sediment and limestone exist along portions of the Atlantic coastal plain in Georgia, South Carolina, and North Carolina. Monitoring stations in those states have begun tracking ground movement, groundwater pressure, and shoreline stability.

Scientists continue to gather data on the collapses, the material washing ashore, and the stability of the broader coastal region.