The blowout in the Pemex well.
"The blowout preventers were closed on the pipe but could not cut the thicker drill collars, allowing oil and gas to flow to the surface, where it ignited and engulfed the Sedco rig in flames. The rig collapsed and sank onto the wellhead area on the seabed, littering the seabed with large debris such as the rig's derrick and 3000m of pipe."
.......
"Two relief wells were drilled to relieve pressure and the well was eventually killed nine months later."

This was the biggest spill so far, .... 3.5 million bbls oil released. Extensive damage on the Texas coast.