It is not a desert in the conventional sense, since it enjoys high rainfall and much of the area is covered by peat overlain with moor grass or by plantations of non-native conifers. There is no exact definition of the border of the Desert of Wales, but it is bordered to the east by the A470 and the town of Rhayader, to the south by the A40 from Builth Wells to Llanwrda, to the west by the A482 from Llanwrda to Pumpsaint, and from there northwards by a series of country roads up to Tregaron. The northern boundary is generally taken as the A44 between Ponterwyd and Llangurig, although the substantial area of moorland to the north of this road, including the reservoirs of Nant y Moch and Llyn Clywedog, has similar topography.
Travel across this area means using one of the few narrow country roads or travelling on foot or on horseback. It is an empty, beautiful area, where the visitor is likely to meet few other people. Although consisting largely of rolling hills, it does also include some gorges and steep valleys with ancient native Welsh Oak forest. This was the area that supported the last native Welsh Red Kites, and still supports their most welcome revival since about 1970.
The area has many lakes and reservoirs, some of which supply drinking water to towns and cities in the West Midlands (Claerwen group of reservoirs), to the towns of North Ceredigion (Teifi Pools), and to towns all along the River Severn valley (Llyn Clywedog).
The ruins of Strata Florida Abbey on the road from Tregaron have a mystical quality, from both the age of the ruins and their location.