MALHAM TARN*, Yorkshire Dales

NATURAL LAKES ARE rarities in the Yorkshire Dales. Water prefers to find subterranean routes through this leaky limestone landscape. But it can’t do that at Malham Tarn, where glaciers scooped down to impermeable slate during the Ice Age. A duck pond by Lakeland standards, it is the largest natural lake in the Dales and the highest marl lake in Britain. Ordinarily, its outflow goes underground at Water Sinks, resurfacing at Aire Head (not Malham Cove, as was previously assumed). Follow the Pennine Way from Malham village for the classic cliff-backed view of this tranquil tarn.