The River Gwendraeth is in Carmarthenshire. It has two almost equal branches that have their confluence in their joint estuary at Carmarthen Bay. The Gwendraeth Fawr (Welsh for large Gwendraeth) is surprisingly the smaller of the two, and has its source in a series of springs to the north of Cross Hands, the most northerly of which rises to the north of Gorslas in the Llyn Llech Owain Country Park, just above the 585-foot (180 m) contour. Below Cross Hands, it skirts the northern edge of Mynydd Mawr Woodland Park, and flows to the south of Drefach. It crosses the 160-foot contour to pass through Pontyberem, Pont Henri and Pontyates, by which time it is less than 33 feet above sea level. Finally, it passes to the south of Kidwelly, to enter the estuary.
The Gwendraeth Fach (Welsh for small Gwendraeth) flows further to the north having its source about 4 miles north of Cross Hands near the 620 foot contour at Penrhiwgoch. Passing under the A48 road, it is soon below the 160 foot contour, flowing in a south-westerly direction to the south of Llanddarog, Cwmisfael and Llangyndeyrn, before turning southwards through Mynyddygarreg. It reaches the estuary to the west of Kidwelly after passing through the town centre.