This amazing, ultra light pack from Osprey is an older version of their current Exos 48. It is designed for through hiking and can carry a TON. This pack has so many amazing features. One that I love is the Air Speed suspensions system in the back, which stabilizes the pack and allows air flow between your back and the pack. The suspension system is so effective I often do not even need to fasten the hip belt.
The bag has a ton of stretchy pockets and straps to attach bulky gear. In the above photo, my sleep system is contained with in the pack. But if you need more room inside, you can attach it to the bottom of the outside of the pack using the straps. The versatility is awesome.
The side mesh pockets are very large and more versatile than most pockets designed just for water bottles.
Inside, there is a clasp and pocket to hold a Camel Back hydration bladder and a slit along the shoulder to run the straw down. It conveniently and securely attaches to the shoulder strap for easy drinking.
As you can see from the photo below, the hose to the camel back bladder secures nicely along the ventilated straps. The straps also feature a place to put your phone (or a candy bar) and a loop to secure walking sticks.
Below you can see the adjustable sternum strap and the whistle feature on the buckle.
A nice feature are the mesh zippered pockets on the hip belt, perfect for snacks or anything else you need handy.