Wales is located on a peninsula in central-west Great Britain. The entire area of Wales is about 20,779 km2 (8,023 square miles). It is about 274 km (170 miles) long and 97 km (60 miles) wide. Wales borders by England to the east and by sea in the other three directions: the Bristol Channel to the south, St George's Channel to the west, and the Irish Sea to the north. Together, Wales has over 965 km (600 miles) of coastline. There are several islands off the Welsh mainland, the largest being Anglesey in the northwest.

The main population and industrial areas are in South Wales, consisting of the cities of Cardiff, Swansea and Newport and surrounding areas.

Much of Wales's diverse landscape is mountainous, particularly in the north and central regions. The mountains were shaped during the last ice age, the Devensian glaciation. The highest mountains in Wales are in Snowdonia, and include Snowdon, which, at 1085 m (3,560 ft) is the highest peak in England and Wales. The 14 (or possibly 15) Welsh mountains over 3,000 feet high are known collectively as the Welsh 3,000s. The Brecon Beacons are in the south and are joined by the Cambrian Mountains in mid-Wales, the latter being given to the earliest geological period of the Paleozoic (Cambrian). Consequently, the next two periods, Ordovician and Silurian were named after Welsh/Celtic tribes from this area.

The summit of Snowdon, Snowdonia, highest
mountain in Wales

The modern border between Wales and England is highly arbitrary; it was largely defined in the 16th century, based on medieval feudal boundaries. It has apparently never been confirmed by referendum or reviewed by any Boundary Commission (except to confirm Monmouthshire as part of Wales in 1968). The boundary line (which very roughly follows Offa's Dyke) separates Knighton from its railway station, virtually cuts off Church Stoke from the rest of Wales, and slices straight through the village of Llanymynech (where a pub actually straddles the line).

The Seven Wonders of Wales is a traditional list of seven geographic and cultural landmarks in Wales: Snowdon (the highest mountain), the Gresford bells (the peal of bells in the medieval church of All Saints at Gresford), the Llangollen bridge (built in 1347 over the River Dee), St Winefride's Well (a pilgrimage site at Holywell in Flintshire) the Wrexham steeple (16th century tower of St. Giles Church in Wrexham), the Overton yew trees (ancient yew trees in the churchyard of St Mary's at Overton-on-Dee) and Pistyll Rhaeadr (Wales's tallest waterfall, at 240 ft or 75 m). The wonders are part of the traditional rhyme:

Pistyll Rhaeadr and Wrexham steeple,
Snowdon's mountain without its people,
Overton yew trees, St Winefride wells,
Llangollen bridge and Gresford bells.

Highest maximum temperature: 35.2°C (95.4°F) at Hawarden Bridge, Flintshire on 2 August 1990.

Lowest minimum temperature: -23.3°C (-10°F) at Rhayader, Radnorshire on 21 January 1940.