The archipelago of Kneiss consists of 4 islets (Dziret el Bessila, Dziret el Hjar, Dziret el Laboua and el Dzira el Gharbia).
The shore of the islands is cut everywhere in soft materials easily attacked by erosion. As a result, despite the low energy of the waves due to the protection afforded by the shoals against the offshore swell and despite the sometimes rather harsh nature of the rock material, subject to the general tendency of regional coastal geomorphology, there is a relatively large setback in the shoreline.
By its location in pre-Saharan Tunisia, this site is also a crossing point for migratory birds from and to the Sahara. 1% of the biogeographic population passes or winters on the Kneiss Islands, which really reveals its great biological importance and the scientific interest that this site could offer to the national and international birding community. The ornithological fauna is important: in fact, 70% of the birds of Tunisia, winter at the level of the Kneiss with a number of birds wintering on this island can exceed, in some years, the 100 000 individuals. For a number of waterbird species, the Kneiss Island Wetland Complex is a key site throughout the western Mediterranean.
The island is not inhabited. The extensive foreshore of the area, highly productive, is traversed during the clam collection period by three to four hundred people who come from the riverside delegations. A small fishing community is located at the Khwala Shelter Area, which is a small bay overlooking the sea. Rowing boats (50) and motor boats (35) form the bulk of the fleet in the area. No agricultural activity on the island of el Bessila; grazing of herds is an activity that is no longer practised in recent years: indeed the island is guarded. Clam harvesting, during the season from November to April, is a well-established tradition in the Kneiss Islands area. It is a predominantly female activity that occupies the youngest segment of the local population and is an important source of income for an average of about 100 families.
The Kneiss Archipelago is situated at the level of a large indentation bordered by large mud marshes corresponding to an ancient estuary. It is surrounded by a huge platform, discovering the shoals very widely during the low-water period. These sandy-muddy shoals are interspersed by numerous tidal channels. The physiognomic originality of the site on a Mediterranean scale is marked by the existence of a very important platform traversed by channels discovered at low tide. This foreshore ecosystem, which is thought to be almost unique on a Mediterranean scale, is by far the most important from a surface point of view.
The Kneiss Islands have a management plan developed by the Coastal Protection and Development Agency (APAL).
Governorate of Sfax delegation of El Ghriba. The Kneiss Islands are located at the Skhira Bay (Sfax Governorate) about 25 km southeast of the town of Mahrès. This archipelago is located about 2 nautical miles (about 3.5 km) from the mainland.