Ceredigion’s rivers rise in the Cambrian Mountains, as do the Severn and Wye – two of Britain’s longest rivers. But unlike the leisurely journey to the sea of the Hafren (Severn) and Gwy (Wye), most of Ceredigion’s rivers rush along short, rapid courses to Cardigan Bay, creating gorges and waterfalls along the way. Ceredigion rivers are famous for their populations of fish, including Atlantic salmon, sewin (sea trout) and brown river trout. Rare bullheads and sea and brook lampreys also inhabit the Teifi. These unusual creatures are one of the oldest animal species on earth.
The Teifi river is internationally recognised as a Special Area of Conservation, partly because it has an important population of otters. Look out for signs of these shy creatures and a range of birdlife including kingfishers and herons.
The Cambrian Mountains are known for their reservoirs, from the historic series of lakes in the Claerwen, Elan and Clywedog Valleys in the east to Nant y Moch and the Rheidol valley in the west. There are regular tours and events at the Elan Valley Visitor Centre, and there's a visitor centre and several great walks for the Rheidol and Nant y Moch reservoirs.
Ceredigion’s uplands are characterised by small lakes, often the remains of glacier activity. Llyn Llygad Rheidol (the lake of the eye of Rheidol) on the north slope of Pumlumon is a moraine-dammed lake occupying a corrie gouged out by ice. On the edge of Cors Caron a kettle pond can be seen be seen, whilst ‘pingo’s (filled in glacial lakes) can be seen at Rhos Llawr Cwrt.
Llyn Eiddwen, on the slopes of Mynydd Bach, and the Teifi Pools above Pontrhydfendigaid are typical of clean, low nutrient upland lakes surrounded by heathland and acid grassland. Look out for floating plants such as water crowfoot and water plantain as well water lobelia, cotton grass and cranberry.