The entire nature reserve lies within the fenced-off enclosure for the fallow deer of the park. It is situated c. 400 m (440 yd) west of Gripsholm Castle and is part of the premises of the castle that is within the right of use of the Swedish king (though it is owned by the Swedish state). A minor part of the deer enclosure is not part of the nature reserve.[3]
The area is hilly, particularly in the north eastern and south western parts of the reserve. The majority of the area is pasture dominated by oak trees. The long continuity of grazing, initially by cattle and later by deer, has created a rich natural environment. The area provides grazing for c. 100 deer. The many old, sometimes dying and decaying, trees — mostly oak but also linden — also provide important habitats for several species of insects, lichen and fungi. Most of the oak trees are around 200 years old, but some are considerably older. Several red-listed species of lichen (e.g. Caloplaca lucifuga, Parmelina tiliacea and Nephroma parile) and insects (e.g. Lasius brunneus, Pentaphyllus testaceus and Corticeus fasciatus) have been found in Gripsholms hjorthage, and the area is deemed to have a high botanical and entomological value. The area is popular as a recreational area, and efforts have been made to maintain what remains of the park laid out in the 1860s, and to install new paths and benches for visitors. It is the only remaining deer enclosure adjacent to a royal castle in Sweden.[2][3][4]
The nature reserve is deemed to be of interest for research concerning species which are dependent on the presence of old-growth oak trees. Gripsholms hjorthage is part of the EU-wide Natura 2000 network of protected areas.[1][2]