The Holnis peninsula in northeastern Schleswig-Holstein, northeast of Glücksburg and located in the Flensburg Fjord, is a diverse nature reserve of great ecological importance. Since April 30, 1993, an approximately 360-hectare section – under protection number 155 – has been protected.
The landscape is characterized by impressive diversity: secluded cliffs, former coastal lakes (Großes Noor and Kleines Noor), salt marshes, spit ridges, beach ridges, and reed beds characterize the area. Some of these landscape forms were created by embankments and rewetting, such as the Kleines Noor, which has been reconnected to the fjord via a dike cut in 2002 and has developed into a valuable brackish water biotope.
The peninsula is of national ornithological importance: Around 65 breeding bird species use the salt marshes and shore areas as their habitat, including shelducks, oystercatchers, lapwings, ringed plover, and terns. Numerous duck species and waders rest here in winter. In addition, the small nature station (NABU hut) not only provides information but also imparts ecosystem knowledge to visitors through weekly bird counts.
The vegetation is equally fascinating: salt marsh species such as samphire, sea aster, sea plantain, and common centaury dominate the landscape, complemented by typical plants such as broad-leaved marsh orchid, marsh sow thistle, and curly dock. The cliffs are home to a colony of sand martins.
The area is part of the FFH (Farmland Conservation Area) "Coastal Areas of the Flensburg Fjord from Flensburg to Geltinger Birk" and is also an EU bird sanctuary. It has been managed by NABU Schleswig-Holstein since 1993, implementing conservation measures and maintenance programs (e.g., grazing with Scottish Highland cattle), and operating a visitor information center.
For those seeking recreation, Holnis offers walks along designated hiking trails—such as the approximately 5.2 km long "Noor Circular Trail"—from vantage points and information stations, where flora and fauna can be experienced in a gentle and informative manner.