The Sea Empress having run aground on rocks just below St Anne's Head, at the entrance to Milford Haven on 16 February 1996.

The Sea Empress was en route to the Texaco oil refinery near Pembroke when she became grounded on mid-channel rocks at St. Ann's Head. Over the course of a week, she spilt 72,000 tons of crude oil into the sea. The spill occurred within the Pembrokeshire Coast National Park – one of Europe's most important and sensitive wildlife and marine conservation areas. It was Britain's third largest oil spillage and the twelfth largest in the world at the time.