Connemara lies in the territory of West Connacht, and, in the past, it was divided into North Connemara and South Connemara by the mountains of the Twelve Bens and by the Owenglin River. It borders on the north with County Mayo at Killary Harbour, a few miles west of Leenane, and on the west and south by the Atlantic Ocean. On the east the boundary meets the rest of County Galway, marked by Invermore River, Loch Oorid and the Maumturks mountains.
Connemara has a wide variety of natural and semi-natural habitats reflecting its geological complexity. Extensive deposits of soapstone, veins of green marble and white quartz can be found in this area.
In the south, hundreds of irregularly shaped lakes, containing many rock knob isles, characterise the boggy landscape. This landscape is also known as Cnoc and Lochan (hill and small lake) terrain.
The coastline and the offshore islands consist of granite and basic rock. The Twelve Bens mountain range, often likened to the Alps, and the Maumturk mountain range consist of quartzite, while limestone forms the bedrock of the western and northern valleys, where prehistoric settlements were concentrated.