Knocksink Wood, National nature reserve and Special Area of Conservation in County Wicklow, Ireland

Knocksink Wood is a protected forest in County Wicklow covering around 52 hectares, marked by densely growing sessile oak on the slopes and a mix of tree species throughout. Springs and small streams flow across the terrain, creating wet areas that define the forest's character.

The forest was designated as a national nature reserve in 1994 and later recognized as a Special Area of Conservation under European protection directives. This status ensures ongoing protection of the woodland and its rare habitats, particularly the petrifying springs.

The Irish name Coill Chnoc Sinche means 'Sinneach's Hill Wood', a reference to a person rather than to the springs. The reserve lies in the Glencullen River valley near Enniskerry, and its former educational centre hosted tours of the wood and gave information to the public before the office closed permanently by 2019.

The reserve lies in the Glencullen River valley near Enniskerry, with springs and water seepage making parts of the ground wet underfoot. The educational centre that once hosted tours and gave information to the public had permanently closed by 2019, though the National Parks and Wildlife Service still listed it in 2021.

The forest holds Ireland's most diverse collection of woodland insects, with rare species found nowhere else in the country. Particularly notable are the petrifying springs, unique habitats protected under European directives.