Though they’re designed for shorter outings, these packs are not as small as many of their minimalist competitors, like the Camelbak Arete 18 Hydration Pack. Even when the 2.5-liter HydraPak ...

A hydration pack is a small backpack with a water bladder inside filled with water that’s easily accessible from the drinking tube, often along the bag straps. A lightweight CamelBak hydration ...