Klackudden is a 107-hectare nature reserve on the coast, 10 kilometres east of Gnarp and one kilometre north of Norrfjärden, in Nordanstig municipality. The Kustleden hiking trail provides a natural route into the reserve, which stretches between the fishing village of Norrfjärden and the holiday-home area of Moningssand.

The forest includes sparse pine woodland on rocky slopes and spruce forest mixed with pine and deciduous trees on richer ground. Much of it has not been logged in recent times, and contains old trees as well as standing and fallen deadwood. The reserve is a habitat for species including violet-grey tagellav lichen, cat-paw lichen and the fungus Porodaedalea pini.

In the northern part, rocky fields on the slopes bear beach ridges formed along earlier shorelines. There are also large erratic boulders and ridges by the present-day shore. Archaeological remains include Bronze Age and early Iron Age burial cairns, as well as traces of settlement at Gamla hamnen. The reserve adjoins Dyråstrand beach at the Dyrån river mouth, where visitors can swim.