Like Hoover and Sellotape, Nalgene are the last word in drinks bottles. Simple, freeze-resistant and leak-proof; they have a big hole at the top for when you want a drink and a lid for when you don't.
Nalgene have been used by mountaineers, climbers, hikers and bikers (not to mention backpackers, office workers, expedition teams and kids) all over the world thanks to their fantastic reputation. BPA free so you can keep healthy and hydrated plus reusing the same bottle is much more sustainable than disposable alternatives.
Not bad for a company that started out making plastic lab equipment in the 1950's that soon gained a following among outdoor types.