1979 Oil disaster in Mexican Gulf.

Volume and extent of spill
From Wikipedia
In the initial stages of the spill, an estimated 30,000 barrels of oil per day were flowing from the well. In July 1979, the pumping of mud into the well reduced the flow to 20,000 barrels per day, and early in August the pumping of nearly 100,000 steel, iron, and lead balls into the well reduced the flow to 10,000 barrels per day. Pemex claimed that half of the released oil burned when it reached the surface, a third of it evaporated, and the rest was contained or dispersed. Mexican authorities also drilled two relief wells into the main well to lower the pressure of the blowout, however the oil continued to flow for three months following the completion of the first relief well.

Pemex contracted Conair Aviation to spray the chemical dispersant Corexit 9527 on the oil. A total of 493 aerial missions were flown, treating 1,100 square miles of oil slick. Dispersants were not used in the U.S. area of the spill because of the dispersant's inability to treat weathered oil. Eventually the on-scene coordinator (OSC) requested that Mexico stop using dispersants north of 25°N.

In Texas, an emphasis was placed on coastal countermeasures protecting the bays and lagoons formed by the barrier islands. Impacts of oil to the barrier island beaches were ranked as second in importance to protecting inlets to the bays and lagoons. This was done with the placement of skimmers and booms. Efforts were concentrated on the Brazos-Santiago Pass, Port Mansfield Channel, Aransas Pass, and Cedar Bayou which during the course of the spill was sealed with sand. Economically and environmentally sensitive barrier island beaches were cleaned daily. Laborers used rakes and shovels to clean beaches rather than heavier equipment which removed too much sand. Ultimately, 71,500 barrels of oil impacted 162 miles of U.S. beaches, and over 10,000 cubic yards of oiled material were removed.

This was called Ixtoc 1. The BP spill will by far be worse. Notice the same dispersants were being used 31 years ago.