Unusual Backpack

Backpacks form an essential part of the gear of the outdoor trekker and the urban backpacker, allowing more mobility and compactness than would be available to someone carrying most of their gear and clothing in a suitcase.
In addition to their use in outdoors pursuits, backpacks are sometimes used in other sports as well. Hydration packs, sometimes used by athletes and military personnel, carry water (in either a bladder or a rigid bottle) and have a tube connected to them from which the wearer can drink without removing the pack; this feature is also included in some more general-purpose hiking backpacks. Backpacks that carry skateboards have also become more popular in the youth culture.
• Backpacks for outdoor activities
One common special type of backpack (sometimes referred to as a "technical pack" or "frame pack") is designed for backpacking and other outdoors activities. These type of packs are more complex than most other backpacks. Compared to backpacks used for more day-to-day purposes such as schoolbooks, such packs are designed to carry substantially heavier loads, and as a result most such packs attach not only at the shoulders but at the hips, using a padded hip belt to evenly distribute the weight of the pack to the legs and back for better balance and comfort (this is a must for long hikes and extensive trips through trails.) The often heavily padded and sometimes semi-rigid shoulder straps are mainly for balancing the weight. They usually (except for those used in ultralight backpacking) have a metal or plastic frame to support and distribute the weight of the pack. Larger packs of this type tend to have a subdivided main compartment. These trekking packs often have several pockets on the outside; they may also have lash points on the exterior (either directly attached to the frame or webbing loops), so that bulky items may be strapped on, although depending on the pack design and type of trek most backpackers will try to stuff everything into the pack. Multiday packs typically have a content between 60 and 100 litres (and are about 3 ft /1 metre tall). Smaller packs with similar features are available for shorter trips.