A camel bag, also known as a hydration pack, is a backpack with a water bladder inside. The bladder is usually constructed of a soft, flexible material and kept in a separate compartment of the backpack. Read more
A tube connects the bladder to a mouthpiece worn over the shoulder, allowing the hiker to drink water without stopping or removing their rucksack.
Camel bags are great for hiking because they keep hikers hydrated without requiring them to carry heavy water bottles. They're also useful because they free up the hiker's hands for other activities like using trekking poles or shooting photos.