Iolo Williamsheads up the Tywi river valley. His 75-mile journey begins at the coastal village of Llansteffan, where the river meets the sea under the watchful gaze of its 12th-century Norman castle. Following the river inland through the fertile lowlands, Iolo visits Bishop's Pond, by Abergwili. At Dinefwr Park near Llandeilo, Iolo heads into the parkland during the autumn for the Fallow Deer rutting season