Glenasmole lies in South Dublin by the Dublin/Wicklow mountains, about 5km from Tallaght. It can be in either the Dublin 18 or Dublin 24 postcode regions. It is best known for Glenasmole valley, a Special Area of Conservation which was formed during the ice age by a glacier and consists of two valleys. The valley has several different habitats which are home to rare plants, mammals and birds. The River Dodder rises in the valley and Maureen's Brook, Cot Brook and Slade Brook join together to form one stream. There are also two reservoirs in the centre of the valley. These are known as the Bohernabreena Waterworks and supply water to 35,000 in the city of Dublin. There are also walking trails in the valley while the village has a national school. Most of the other major services and amenities can be found in nearby Tallaght, which is just 7km away.