Oxwich Bay (Welsh: Bae Oxwich) is a bay on the south of the Gower Peninsula, Wales.

Its landscape features sand dunes, salt marshes and woodland. Oxwich Bay includes a 2+1⁄2-mile (4 km) long sandy beach, accessible from the village of Oxwich. It is a popular spot for swimming and watersports including diving, sailing, water skiing and windsurfing.^[1] There is a public footpath along the cliffs from Oxwich Bay, around Oxwich Point, and to Port Eynon Bay. Buses run every couple of hours between Oxwich and Port Eynon.^[2]

A wetland site at the rear of the dunes forms Oxwich Burrows National Nature Reserve.^[3] The dunes are crossed by a small stream called Nicholaston Pill.^[4] The bay ends at the eastern end with the cliffs of High Tor; but at low tide, a continuous sandy beach connects with Three Cliffs Bay beyond.^[5] Within the nature reserve there are rare plants such as the dune gentian and the round-leafed wintergreen, insects such as the small blue, beachcomber beetle and the hairy dragonfly while the wetlands are important for birds, a bird hide is located at Whitestones which is accessed by a boardwalk through the wetlands. The birds present include water rail, little grebe and wildfowl, as well as the occasional wintering great bittern.^[3]

Submarine cables leave the mainland of Britain from Oxwich. These include the SOLAS cable across the Irish Sea, and the TAT-11 and Gemini North transatlantic telephone cables. These latter two do not terminate here but instead continue on to France (TAT-11) and England (Gemini).^[6]

On 1 February 2007, Oxwich beach was named the most beautiful in Britain.^[7]