© Duncan Hutt
Cresswell Pond is a large brackish lagoon that has been created as the result of subsidence from old collapsed mine works. As the pond is adjacent to and connected to the sea, it has developed into a shallow brackish lagoon, providing excellent feeding for wading birds all year round.
It is particularly good during the spring and autumn passage when rarities often occur. Avocets nested here in 2011, the most northerly site in the UK. Large numbers of waterfowl often roost here, with small numbers of greylag and pinkfooted geese. The majority of the site is the lagoon but there are areas of reed bed, two smaller ponds, a path and boardwalk leading down towards a bird hide. Due to the brackish nature of the pond, it is a rare habitat type within Northumberland. The invertebrate species present there are part of the reason why the site has been designated a SSSI, the invertebrate community is a mixture of both fresh water such as Jenkins' spire snail and salt water species, notably sandworms. Along the eastern edge of the pond is a reed bed the dominant species being common reed. Within the pond are two plant communities, the submerged plants and saltmarsh flora. The submerged pond plant species beaked tasselweed is present and the saltmarsh community consists of aster, sea milkwort, sea arrowgrass and common saltmarsh grass. In the field to the south of the large pond are two smaller fresh water ponds one of them is dominated by glaucous bulrush and common spike-rush and the other is dominated by branched bur-reed. These ponds have resident populations of moorhens and coots and they provide a very valuable place for passage migrants.