Llansteffan (originally Llanstephan) lies 7 miles south of Carmarthen on the west side of the Towy estuary. The beach is mostly sand and cockle shells backed by an area of rough grass, behind which are the (free) car parking areas. An asphalt path with plenty of benches and picnic tables runs along the back of the beach. Beach access is down a short slipway. The sandy beach continues northwards for about a mile up the estuary. To the south the sand continues to Scott's Bay, backed by low cliffs of sandstone and siltstone. Signs warn against attempting to cross the estuary and swimming, although swimming is generally safe at high water before the tide turns. Further beach access is available along a lane from Llansteffan village which runs right onto the beach about 100 yards south of the main car park, and dog restrictions apply from here to a point roughly 100 yards before the northern car park.
Beach facilities include toilets ♿, a small play area, fish and chip and ice cream vendors and a tea room / beach shop. Llansteffan village is a short walk away and has two pubs and a village store. A passenger ferry service now operates across the river to Ferryside, which has a rail station.
Overlooking the beach and village is the imposing Norman castle. Officially the opening times are 10.00 - 16.00, but as there's no gate of any kind access is possible at any time. One of its two remaining towers is accessible, and has good views up the Towy estuary.