Ynys-hir RSPB reserve is a nature reserve of the RSPB situated beside the Dyfi estuary in Ceredigion, mid Wales between Aberystwyth and Machynlleth. The reserve covers 550 hectares and includes a variety of habitats extending inland from mudflats and salt marsh through farmland and pools to oak woodland and hillside scrub. Facilities include a small visitor centre and seven hides.