Coordinates: 50°49′13″N 0°20′18″E / 50.8203°N 0.3383°E / 50.8203; 0.3383

Pevensey is a village and civil parish in the Wealden district of East Sussex, England. The main village is located 5 miles (8 km) north-east of Eastbourne, one mile (1.6 km) inland from Pevensey Bay. The settlement of Pevensey Bay forms part of the parish.

The village of Pevensey is located on a ridge of land, which juts out onto marshland. Until the 13th century the marshes were an inlet of the sea, extending inland as far north as Hailsham and eastwards to Hooe; it was studded with small areas of high land which became islands at high tide: and having the place-names — in addition to Peven’s ey — of Rickney, Horse Eye, and North Eye. All are derived from the Old English word "ey" meaning island.

With the effect of longshore drift this large bay was gradually cut off from the sea by shingle, so that today's marshes are all that remain behind the shingle beach.

The marshes, known as the Pevensey Levels, cover an area of around 47 miles² (120 km²). They are a Site of Special Scientific Interest and a large nature reserve, jointly owned by Natural England and the Sussex Wildlife Trust. There are many nationally rare plants and invertebrates, including the fen raft spider. The site is very fragile and general access is not permitted.

The area known as the Pevensey Levels is a Site of Special Scientific Interest (SSSI) notified under Section 28 of the Wildlife and Countryside Act 1981. It is an area of marshland situated between Bexhill in the east, Pevensey in the west and Hailsham in the north. The site covers an area of 8,650.9 acres (3,500.9 ha).

The area is a conservation area owned jointly by Natural England and the Sussex Wildlife Trust. There are many nationally rare plants and invertebrates, including the fen raft spider. The site is very fragile and general access is not permitted

At the end of the last glaciation, about 10,000 years ago, rising sea-levels flooded the lower reaches of the numerous coastal river valleys in the Pevensey area. This resulted in the creation of a tidal estuary with a wide bay. The present Levels were under water.

Over hundreds of years, the Levels gradually changed from saltmarsh to reedy meadows although much of the area was still under water as recently as 700 to 800 years ago.

(PDF) SSSI Citation — Pevensey Levels. Natural England. http://www.english-nature.org.uk/citation/citation_photo/1000914.pdf. Retrieved 2008-10-12.