BULL SAND FORT, Humber Estuary. Aerial view. Standing one and a half miles from shore off Spurn Head on a submerged sandbank, it stands 18 metres high and 25metres in diameter. Bull Sand Fort and its twin Haile Sand Fort were built in 1914 to protect the mouth of the Humber from enemy attack. They were completed just as the First World War broke out. They were also used in the Second World War as anti-aircraft and anti-submarine defences.