Beaufort's Dyke

[3] Because of its depth and its proximity to the Cairnryan military port, Beaufort's Dyke became the United Kingdom's largest offshore dump site for surplus conventional and chemical munitions after the Second World War: it had been used for the purpose since the early 20th century.

Over the previous five years, anti-tank grenades had washed up on the shores of Northern Ireland and the Isle of Man.

[7] According to documents from the Public Record Office, approximately two tonnes of concrete-encased metal drums filled with radioactive laboratory rubbish and luminous paint were dumped in the dyke during the 1950s.

[8] Projects for a tunnel or Irish Sea fixed crossing between Northern Ireland and Scotland have been suggested at various times from the late 19th century onwards.

[6] Explosive ordnance advisers Exord cast doubt on the Portpatrick route saying "any intrusive works such as piling associated with the construction of bridges would pose an unacceptable level of risk".

Beaufort's Dyke, highlighted in blue, on a 1969 Admiralty chart
Map showing the size and location of Beaufort's Dyke, in red, between the coasts of Northern Ireland and Scotland
Beaufort's Dyke, showing the position of the munitions dump, from an Admiralty chart published in 1947. Depth in fathoms