Walking shoes / boots, wet-weather clothes, warm-weather clothes -- this is England, the climate is changeable !
Available locally
Definitely bring your camera and spare batteries / memory card if it's digital.
A good map and guide are essential, there's so much to see in the Yorkshire Dales -- Ordnance Survey Tour maps are good, they're clear and show places of interest and the Ordnance Survey / AA Leisure Guide series have lots of information and suggestions for walks and drives -- both available from large book shops like Waterstones.









