Nynäs nature reserve is located in both the municipality of Trosa and Nyköping, and consists of a varied cultural landscape with woodland forests, hazelnut bushes, fields, beach beds and other vegetation types. The area, apart from the rich nature is also of great importance for outdoor life. There are well-developed hiking paths and trails. Nynäs is part of the ecological network Natura 2000.
Nynäs nature reserve, including the sea area is 10 times larger than the town of Trosa. The area includes a variety of natural habitats, cultural historical sites, ancient remains and old farms with great opportunities for outdoor activities such as swimming, boating, fishing, hiking and cycling. To get a feel for the area we suggest a tour starting at the castle, then further along the south coast over Brevik and Sandvik, then north to Långmaren north east of Rundbosjön and finally Karlfors mill. Then you have seen quite a bit with very varying environments - yet only a fraction of what the area holds.