Location
The refuge is located in Western-Pomeranian voivodship, in the counties of Swinoujscie and Kamien. It is the central part of "Uznam i Wolin" mesoregion.

Ecosystem
Geologically it is a young structure. It began to form after withdrawal of the last glaciation. Initially waters from the south were flowing freely to the Baltic Sea, through wide gates between islands Wolin and Uznam. Gradually big moraine islands became enclosed from the north with sands of a lagoon which almost connected both islands along the shore. Blocking free flow of the river's waters caused accumulation of material carried with current on south foreland of the islands inside a reservoir of present Zalew Szczecinski. Nowadays the estuary consists of many natural branches of the Swina - the east branch of the Odra, as well as about 44 islands of different sizes. The Swina river is the main outflow of the Odra waters to the Baltic (over 75%).

Islands of the delta, made from silt and water sands, elevate a little above water level. Only one of them - Wielki Karsibor - is inhabited, economically exploited and encircled by a levee. Others islands are uninhabited. In the past those located closest to the land used to be exploited as pastures.

Specific feature of the Delta waters is mixing river and sea waters and occurrence of so called "cofka" (pushing sea waters into the river's estuary during long-lasting northern winds). This phenomenon makes the islands, which are located lower, being constantly exposed to influence of salty waters. Most of the islands is covered by natural meadow and pastures vegetation as well as reed fields.

Characteristic feature of the estuary's plant cover is presence of vast communities of halophilic vegetation, mainly common reed and saltmarsh rush. It is one of a few stands of this vegetation preserved on the Polish coast. Forests cover a bit over 25% of the setsuary's area. They occupy edges of the refuge, forming wide belt along west and north-west border of the refuge. Swampy places are occupied by alder communities,. On the south of the island of Uznam, on the part adjoining to Kanal Piastowski (the Piast Canal), there is located large area of silting fields, banked up with sand dug out during deepening of a fairway between ports of Swinoujscie and Szczecin. Minute part of the area, situated on Karsibor and Wolin islands, in north-west part of the refuge, is occupied by arable lands. The biggest village located within the refuge is Karsibor. Other bigger villages lie on big islands - Wolin and Uznam.

Characteristic feature of Delta Swiny is richness of bird species. Delta is the most important in Pomerania region breeding place for the aquatic warbler. It is a relic of a westernmost population of aquatic warbler in Europe. In order to protect this species, as well as numerous wading birds the National Society for the Protection of Birds(OTOP) established one of the first Polish public reserves.

Occurrence of four species of birds qualify Delta Swiny as international birds refuge. These are smew and common merganser, occuring in large numbers during migrations, as well as hatching white-tailed eagle (5-6 pairs) and aquatic warbler (about 60-70 males singing during spring mating). Many species of birds specified in 1 Appendix of the Habitats Directive have been observed in Delta Swiny. It is a hatching place for bittern, little bittern, black stork, honey buzzard, black kite, red kite, marsh harrier, osprey, spotted crake, crane, dunlin, ruff, Mediterranean gulf, whith-wniged tern, common tern, Montagu's harrier, corn crake, Eurasian eagle-owl, short-eared owl, Eurasian nightjar, great spotted woodpecker, middle spotted woodpecker, wood lark, red-breasted flycatcher. Delta Swiny is also and important place for birds migrating along the Baltic shore and wintering.

Threats
The main threat is abandonment of previous agricultural use, mainly pasturage and meadows mowing, spring plants burning, commercial reed logging (due to a few years long  winter mowing a monoculture of reed "plantation" has become to appear). Another threat comes from chaotic subarban and recreational development along the lagoon's shore and the river, and connected with it development of water sports, especially motorboating.

Nature protection
Part of Delta is protected within Wolinski Park Narodowy (the Wolin National Park) and "Krasiborskie Paprocie" nature reserve. There are also social forms of protection of nature, the OTOP reserve "Karsiborska Kepa" mentioned above, as well as the reserve of European Union of Coastal Conservation - Poland - "Bielawki".