On 5 August 1973, the tanker Dona Marika was anchored in the entrance to Milford Haven harbour. During the night, her anchor was dragged from its original position, because of very stormy weather. The vessel ran aground on rocks near Great Castle Head, Dale Roads, and spilled 3,000 tonnes of petrol. All 38 crew members were rescued.
The spill took place in a semi-enclosed area in bad meteorological conditions. The risks of explosion and of poisoning from the vapours were high. The leak was stopped by foam injection. The Dona Marika was then towed to a place where unloading could be carried out safely. The petrol remaining in the tanker was unloaded. However the refloating operation was difficult and lasted until 13 November. The vessel was then towed to Falmouth in Cornwall, where she was declared a constructive total loss, due to the extent of the damages. She was sold to Spanish shipbreakers and was taken in tow to Alicante where she was demolished.
There was significant loss of shellfish and molluscs from the rocky shores. This incident was also followed by considerable proliferation of green algae (enteromorpha). A number of long-term studies were conducted in the area. In 1979, the site had almost entirely returned to normal.
Name: Dona Marika
Date: 5 August 1973
Accident area: entrance to Milford Haven harbour
Cause of spill: grounding
Quantity transported: 5,000 tonnes
Type of pollutant: petrol (U.S. gasoline)
Quantity spilled: 3,000 tonnes
Ship type: oil tanker
Date built: 1954
Shipyard: Kaldness MV AS, Tonsberg
Length: 168.34 m
Width: 21.41 m
Draught: 12 m
Owner: Hermes Navegacion SA
Last update: April 2006