North Sealand has many forests and woods. At 5,600 hectares, Gribskov is the fourth largest forest in Denmark. Gribskov was originally shared between the Church and the Crown, but after the reformation it became solely owned by the Crown. Up until the 18th century, Danish monarchs used the area mainly for hunting and to graze horses from the famous Frederiksborg stud farm. Forestry became the predominant activity in the area after the 18th century. “Grib” is an old Danish word that translates as 'common' – a piece of land which everyone could use, which had no specific owner. 

Hornbæk Plantation, part of Kronborg state forest district, is a young forest compared to the other state forests in North Sealand. The first pine trees were planted in an area of 14 hectares in spring 1793, and most of the plantation was planted over the next fifty years. The planting was originally done to prevent drifting sands.

Store Dyrehave is marked by its royal history. The forest paths were constructed in 1670–1680, formed as long hunting routes that meet in star formations. For a time, Store Dyrehave was also used for the summer grazing of the famous Frederiksborg horses.

Tisvilde Hegn is a state-owned nature reserve in North Sealand, stretching along the Kattegat coast, from Tisvildeleje to Asserbo and Liseleje. The area was plagued by drifting sand from about 1500, and many farms were abandoned in the 18th century because the soil could no longer be cultivated. The first attempts to stop the sand from drifting were made around this time and by 1800 the first plantations were planted.

Grønnesse forest covers together with forest areas belonging to the farm Grønnessegaard 133 acres. It is the biggest forest area at Halsnæs. The forest is beautiful and very varied with several wetlands. The forest has a large population of deer and red deer.

Arresødal forest lies with Vinderød forest on the hills between the city of Frederiksværk and Arresø (the lake).
The local forest in the middle of Frederiksværk makes a green area that is unique. In the Arresødal Forest 90 % of the trees are leaf-bearing trees. The forest has for many years been like a park. Today most of the forest is untouched. Through the forest there are paths that leads you all the way to Arresø; the biggest lake in Denmark.