On November 20, 1980, a drilling rig on Lake Peigneur in Iberia Parish, Louisiana, accidentally punctured the ceiling of a salt mine located roughly 300 feet below the lakebed. The resulting chain of events drained the lake and caused significant destruction, though no lives were lost.

Lake Peigneur was a shallow, freshwater body of water spanning about 1,300 acres, with an average depth of 10 feet. The Diamond Crystal Salt Company had operated a mine beneath the lake for more than 50 years, extracting salt from a large underground salt dome.

The Wilson Brothers Corporation had set up a floating drilling rig on the lake to search for oil. At around 3:00 a.m., the drill bit penetrated the ceiling of the mine. This created a hole that allowed lake water to pour into the tunnels below. Because salt dissolves easily in water, the opening quickly widened, which increased the flow of water and accelerated the erosion.

The drilling crew noticed the rig beginning to tilt and saw a whirlpool forming around the platform. They evacuated by boat and reached shore without injury. Shortly afterward, the rig was pulled beneath the surface.

Inside the mine, workers felt vibrations and heard the sound of water. The foreman ordered an immediate evacuation. The tunnels were dry and normally stable, but the situation deteriorated quickly. All 50 miners reached the surface through elevators and emergency ladders before the mine flooded.

As the water continued to drain, the whirlpool expanded. Several barges and a tugboat that had been moored on the lake broke loose and were pulled into the vortex, along with docks and other equipment. The shore began to collapse, and large sections of the nearby botanical gardens on Jefferson Island slid into the lake. An estimated 65 acres of land, including greenhouse complexes and centuries-old live oak trees, were lost.

The lake remained connected to the Gulf of Mexico through the Delcambre Canal. As the water level in the lake dropped, the flow in the canal reversed, drawing salt water from Vermilion Bay and the Gulf back into the lake. This reverse current lasted about three days. By the time it stopped, the lake had been transformed from a freshwater body into a saltwater one, with depths in some areas exceeding 400 feet.

Investigations determined that an error in drilling coordinates led the drill bit to intersect with the mine tunnel. The exact source of the error became the subject of legal disputes between the companies involved. Insurance settlements eventually totaled more than $45 million.

The Diamond Crystal Salt Mine was a total loss and never reopened. Rescue efforts were not needed: all 55 people involved in the incident survived. Several factors contributed to this outcome, including the timing of the event during a shift change, the immediate evacuation response, and the gradual nature of the structural collapse, which provided enough warning time.

The disaster led to stricter coordination requirements between surface drilling operations and underground mining. It also became a case study in emergency preparedness and the importance of accurate spatial data for industrial safety.

The botanical gardens on Jefferson Island were partially restored over time, though the landscape around the lake remained visibly changed. The lake has since developed a saltwater ecosystem and continues to be used for fishing and recreation, though its character is fundamentally different from what it was before the collapse.