More than 6000 years ago, the sea rested against a strip of terminal moraines, in which lies, among others. Rowokół, creating a shallow and vast bay. Sea currents were constantly depositing sand and building a spit, cutting off the bay. Its closing took place 5500 years ago. Thus, a large coastal lake was created, whose waters drained fairly quickly. The gradual and uneven overgrowth of the lake and the deposition of thicker and thicker deposits of silt and peat led to the formation of four lakes: Łebsko, Gardno, Dolgie Wielkie and Dolgie Małe, and to produce a flat one, vast, wet and peaty coastal plain. In recent years, the formation of a fifth lake can be observed (Smołdziński), formed as a result of cutting off the bay in the north-eastern part of Lake Gardno. The waters of the two largest lakes of the Słowiński National Park – Łebska (7140 ha. 3. the largest in Poland and the largest of the coastal areas) i Gardna – (2468 ha) they are fertile and not very clean. The Łeba River flows into Łebsk, a do Gardna – Łupawa. For shallow (Łebsko – 6.3 m, Gardno – 2,6 m) and silted lakes, they carry significant amounts of pollutants. Within 60 years, the area of Łebsko decreased by 400 ha. The periodic inflow of sea waters is characteristic of both reservoirs, Therefore, species of halophilous plants and animals also live here.
A characteristic feature of the Słowiński Coast is the great variety of plant communities – away from the sandy grasslands, moors and pine forests to peat bogs, swamp forests, alder forests and small fragments of beech and oak trees. There is a sandworm in the dunes, sand cake, gray brush and seaside Santa Claus. Older dunes are overgrown with patches of maritime bushberry with Scots pine. On the Czołpińska Dune you can find dwarf mountain pine – type, which was introduced here artificially to consolidate the dunes. The lake Dołgie Wielkie is extremely interesting from the botanical point of view. There are numerous strictly protected relict plants here, e.g.. underwater fern – lake poreblin and single-flower marguerite. On Lake Dołgie Małe, a peat field develops, that is, a sheepskin coat floating on the water” built of sphagnum, on which red rosettes of the insectivorous roundleaf sundew are visible. We encounter raised bogs near the Łebsko and Gardno lakes. Cloudberry is an interesting and rare plant, which is a relic of the Ice Age. Between the Łeba and the estuary of the Piaśnica there is a unique reserve called “Choczewskie Cisy”, with the only natural site of these trees on the Słowiński Coast, the peat reserve "Białogóra” and "Piaśnickie Łąki” – elephant plant community with the participation of Atlantic species.
Water bird reserves have been established on the Łebsko and Gardno lakes – “Żarnowskie Łęgi”, "Gackie Łęgi” and "Cieminskie Błota”. The breeding grounds have here, among others: variable daddy, remiz, the mustache, Montagu's harrier, crane, lonely paddling pool, great crested grebe, mute swan, seagull. Deer live in the forests, sarny, wild, borsuki, kuny, ermine, squirrels. In the vicinity of the lakes, you can meet beavers and otters. Fladry occurs in the lakes due to the periodic infusion of seawater, herring, cod, flatfish, sprats, eels, salmon, as well as freshwater species – perch, pike perch, płoć, bream, pike and burbot.