Whatever your outdoor activity is, a pair of binoculars or a monocular will come very useful. A pair of binoculars will give you a better view at sporting events such as horse riding, or to view birds in the garden. Bincoulars will give you the extra detail on your object so that you can enjoy the experience better.
A pair of bincoulars or a monocular is very useful when out walking or hiking. Make sure you can enjoy the view with a pair of clear binoculars. If weight is an issue, then a monocular will give you the same view without the bulkyness of a pair of binocualrs.