The Wantsum Channel is the name given to a now silted-up watercourse separating the Isle of Thanet and what was the mainland of the English county of Kent, forming a major shipping route from the English Channel to the Thames estuary. The "river" Wantsum is now little more than a drainage ditch lying between Reculver and the River Stour.
From prehistory until the Middle Ages, the Wantsum Channel was joined by the River Stour, which entered it at Stourmouth close to its midpoint; it was a two-mile-wide (3.2 km) strait. The southern end of the channel met the sea at Richborough (Roman name, Rutupiae), downstream of Sandwich, while the northern end met the Thames Estuary at Reculver (Roman name, Regulbium). That the Romans chose both sites for forts indicates the significance of the route, which their shipping commonly used to travel between London and the continent; and which Vikings used to raid Canterbury in 839 AD.
Deposition of shingle at Stonar, at the southern end of the Channel, gradually caused it to silt up; and shipping heading for Canterbury, formerly using the northern entrance, brought Fordwich into prominence as its outport. The silting up continued, particularly during the 12th and 13th centuries, when Augustinian monks entered into land reclamation; eventually, by the 16th century, the Wantsum Channel had dried up apart from the large drainage ditch down the centre of the erstwhile channel and its feeder ditches: the wider parts often referred to as the River Wantsum. However, that is only the northern section for, where the River Stour formerly emptied also to the north, its southern estuary could also be considered part of the Wantsum
Efforts made by the monks of Minster-in-Thanet to manage the Wantsum in the Middle Ages are reflected in two names for parts of the Channel/Stour, Abbot's Wall, and Monk's Wall. During the 18th century, silting threatened the rich port of Sandwich and efforts were made to create sluices and channels to control the waters. These ultimately failed, and as a result Sandwich is now some distance from the sea. In time, coastal erosion washed away most of the fort at Reculver, though parts of the western wall can still be seen close to the church towers. This church was founded in about 669 AD, long after the Romans had departed, the two towers being added in the 12th century. By the time Bede wrote his Ecclesiastical History of the English People, in about 731 AD, the northern outlet of the Wantsum had become known as the "river Yenlade". The church was demolished in the early 19th century, leaving just the towers as an aid to shipping. The towers and the remains of the fort are essential viewing for the tourist.