Seymour Tower is the furthest offshore of Jersey's 18th century fortifications, built to protect the island against invasion from France. However, built after the French attack in 1781 which was defeated in The Battle of Jersey, it was never to see action.
The islet L'Avarizon on which it stands is about 2 kilometres out to sea from La Rocque Point, but such is the extreme rise and fall of the tide on Jersey's east coast that the tower is accessible across the sand and rocks at low tide, which has led to numerous people being cut off by the rising tide over the years and having to be rescued or losing their lives. In February 1987 two riders and their horses, who became lost when a thick fog descended without warning, famously took refuge on the base of the tower itself and the horses could only be persuaded to come back down after a sand ramp had been constructed by excavators.
The tower was built the year after the French landed at La Rocque and although it has been suggested that it was named after the Governor, General Henry Seymour Conway, who initiated the construction of Jersey's coastal towers, it is more likely that it was named for Sir Edward Seymour, Governor in 1540 when an earlier tower was constructed at this location.