Abermawr is a stretch of coastline and is regarded as a Site of Special Scientific Interest in Pembrokeshire, Wales.

During the 1840s, the South Wales Railway (SWR), led by engineer Isambard Kingdom Brunel, began to explore ways of constructing a rail link to the coast, opening up a passenger train route from London via the Great Western Railway to link with passenger ships sailing from Great Britain to Ireland and to America.

In 1847 Captain Christopher Claxton surveyed the St George's Channel to try to ascertain the best route for passenger ships to cross.

The cable was laid by Brunel's steam ship Great Eastern between Trinity Bay in Newfoundland and Valentia Island in Ireland.

[7] During World War I the site was important in communicating with North America[clarification needed] and was guarded by a small detachment of soldiers.