1. Trekking Pole
Trekking poles are extremely useful when hiking; they help people maintain balance while taking pressure off of the knees and ankles.
Binoculars are great for sight-seeing, but they are also important for helping hikers plan their route and foresee potential problems and obstacles.
Sunglasses aren't just a fashion statement; they help hikers protect their eyes from Ultraviolet rays and Infrared rays (particularly at high altitudes).
4. Balaclava (Face Mask)
Face masks are a must for hikers, especially in severely cold conditions. In below freezing temperatures below the head loses more heat than any other part of the body; these masks help prevent that heat loss.
5. Hydration Packs
Hydration packs are great for hikers because they allow for "hands free" hydration without forcing the hikers to lose momentum when stopping for a water break.