When a Texaco oil rig mis-triangulates its drilling position and hits a nearby salt mine full of workers, an entire lake complete with homes, barges, and land drain into the enormous sink hole. Soon the river reverses direction and brings in water from the ocean, swallowing up more land.

At that time, Diamond Crystal Salt Company operated the Jefferson Island salt mine under the lake, while a Texaco oil rig was drilling down from the surface of the lake searching for petroleum. Due to a miscalculation, the 14-inch drill bit entered the mine, starting a remarkable chain of events which at the time turned an almost 10 foot deep freshwater lake into a salt water lake with a deep hole. (extracted from wikipedia)