The MV Sea Empress was a single-hull oil tanker

Oil tanker

An oil tanker, also known as a petroleum tanker, is a merchant ship designed for the bulk transport of oil. There are two basic types of oil tankers: the crude tanker and the product tanker. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries...

 that ran aground near the southwest coast of Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

 in February 1996. The ensuing oil spill

Oil spill

An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is mostly used to describe marine oil spills, where oil is released into the ocean or coastal waters...

 affected a considerable area of nearby coastline.
Pembrokeshire was suffering for over a year after the incident. Most of the birds in the area died and the oil made tourist-dependable beaches very ugly and black.
On the evening of 15 February 1996 the Sea Empress was entering the mouth of the Cleddau Estuary on her way into Milford Haven

Milford Haven (harbour)

Milford Haven Waterway is a natural harbour in Pembrokeshire, West Wales. The Haven is a ria or drowned valley flooded at the end of the last Ice Age. formed by the Pembroke River and the Daugleddau estuary, and winds west to the sea...

 in Pembrokeshire

Pembrokeshire

Pembrokeshire is a county in the south west of Wales. It borders Carmarthenshire to the east and Ceredigion to the north east. The county town is Haverfordwest where Pembrokeshire County Council is headquartered....

 to deposit its oil cargo at the Texaco oil refinery

Pembroke Refinery

The Pembroke Refinery is an oil refinery situated on the Pembrokeshire coast in Wales at Rhoscrowther in the community of Hundleton. It first came on stream in 1964. The refinery has a fluid catalytic cracking unit that came on stream in 1982. The refinery also has an HF Alkylation unit,...

.