Covering Llanidloes & the source of the River Severn (Afon Hafren) OS Explorer Map 214 covers an area that's popular due to the wide choise of foot & cycle paths. The area in & around Clywedog Reservoir (Llyn Clywedog) offers activities from walks, dingy sailing & fishing. With this map you will receive a code for use on your i OS or Android smartphone or tablet. Find our more at Mobile Download FAQ. The OS Explorer map for Llanidloes & Newtown is available in both the standard paper version & weatherproof ' Active' version.