Langebaan Ramsar site is situated approximately 100 km northwest of Cape Town and includes the islands Schaapen (29 ha), Marcus (17 ha), Malgas (18 ha) and Jutten (43 ha), the Langebaan Lagoon (15 km long and 12.5 km wide), and a section of Atlantic coastline. The lagoon is entirely marine with a relatively stable salinity and supports dense populations of molluscs and crustaceans as well as 71 species of different marine algae. The lagoon also serves as a nursery for the development of juvenile fish, and gobies (Gobiidae), klipfish (Clinidae), pipefish (Syngnathidae), skates, rays and small sharks are common.

The extensive intertidal area of the lagoon supports up to 55 000 waterbirds in summer, most of which are waders (23 species), including 15 regular Palaearctic migrants. The most abundant Palaearctic waders are the curlew sandpiper Calidris ferruginea, grey plover Pluvialis squatarola, turnstone Arenaria interpres, knot C. canatus and sanderling C. alba. The most important resident waders are the whitefronted plover Charadrius marginatus, Kittlitz's plover C. pecuarius and chestnutbanded plover C. pallidus. About 400 black oystercatchers Haematopus moguini, which comprises 12% of the global population, are found in the Langebaan area.

The five islands of Saldanha Bay to the north of the lagoon provide a home for nearly a quarter of a million sea birds, many of which are endemic to the nearshore regions of South Africa and Namibia. Cape gannets Monis capensis and Cape cormorants Phalocrocorax capensis are abundant and the largest known colony of kelp gulls Larus dominicanus in southern Africa is found on Schaapen Island.