Thermal Liner For Mountaineering: 7 Best Picks For UK Climbers (2026)

A climber sliding into a thermal liner for mountaineering during a winter bivouac

What is a thermal liner for mountaineering? It is a lightweight, sleeping-bag-shaped inner layer, made from hollow-core synthetic fibre, fleece, merino or silk, that slides inside your bag. It adds a few degrees of warmth, blocks draughts, keeps the bag clean and costs a few hundred grams. That’s cheaper and lighter than buying a heavier … Read more