The Fens NCA is an area of wide, low-lying open landscapes stretching from the southern edge of Greater Lincolnshire, and the western shores of The Wash to central Lincolnshire. Landward, it is a vast flatland surrounded on three sides by slightly raised, gently rolling hills and vales from which a few rivers flow across the plain to the sea.

Once the largest wetland area in England, it has been drained to become a nationally important farming landscape. The area is characterised by a network of heavily managed rivers, drains and ditches draining into The Wash. As a result of agriculture-related drainage, the range and extent of once abundant peatland habitats, such as fen and other wetland habitats, have greatly reduced.

Woodland cover is sparse, and trees and hedgerows are occasional, found mainly in the vicinity of farm buildings and older settlements. The area’s drainage system is an important network of slow-moving waters and bank-side vegetation, often accompanied by roads, some railways, and their associated linear fringing mainly grassland habitat. The waterways are important for connectivity with other NCAs in the central England. 

There are few significant urban areas, with widely dispersed villages along the roads and waterways, and isolated farms and dwellings across the rest of the area.