River Cuckmere

River Cuckmere
Looking West over Cuckmere Haven
Country	England (East Sussex)
Basin features
Main source	Near Heathfield
River mouth	English Channel

The River Cuckmere rises near Heathfield in East Sussex, England on the southern slopes of the Weald. The name of the river probably comes from an Old English word meaning "fast-flowing", since it descends over 100 m (328 ft) in its initial four miles (6.4 km). It flows into the English Channel, and has the only undeveloped river mouth on the Sussex coast.

The river has many tributaries at its upper end, the principal one being the River Bull; and its main channel begins at Hellingly. After crossing the Low Weald area of farmland, the Cuckmere cuts through the South Downs in its own valley. It reaches the English Channel at Cuckmere Haven, between Seaford and the Seven Sisters cliff face. The lower part of its course in the floodplain is marked by meandering. The Cuckmere Valley Nature Reserve is located in the lower estuary portion of the river. The valley is very important for nature conservation. It has been designated a Site of Special Scientific Interest and is part of the South Downs National Park.

The Cuckmere Valley civil parish takes its name from the river. In the 19th century, defensive measures were taken to prevent flooding of the upper valley. Shingle was regularly dug from the mouth of the river and the banks were made higher. In 1846, the course of the river was straightened in an artificial cut; the cut mostly prevented flooding upstream, which used to reach to the village of Alfriston. It also provided support for irrigation. In addition, raised river banks, or levees, were constructed to protect areas from flooding. In recent decades, the area has become a major tourist destination, with tourism contributing to the local economy more than does agriculture.