An area of rough grazing, reedbeds, open water and scrub on the northern edge of Langstone Harbour, enclosed by a seawall.

Primarily of bird interest, with massive flocks of Dark-bellied Brent Geese, other wildfowl and thousands of waders in winter (including Knot), and many passage waders in season, notably Curlew Sandpiper, Little Stint, Spotted Redshank and Ruff. Passerine migrants are often found too, and breeding birds include Bearded Tit and Acrocephalus warblers. Passage and wintering raptors are frequent - Ospreys are annual. Wryneck, Pectoral Sandpiper, Spotted Crake and Aquatic Warbler are annual or near-annual visitors. The reserve is also of significant botanical and entomological interest.

Recent rarity highlights include Collared Pratincole, Wilson's Phalarope and Barred Warbler.