This Romanian Army Haversack is a great find. and great design. Inside there are two parts, a larger 3/4 area, and a smaller 1/4 are. The smaller area is larger enough for any canteen. Nalgene, US Army 1qt, Swiss Army, any canteen. 1.5 liter easy. see picture
The main part fits everything else. well constructed, bomb proof.
Heavy cotton duct material and leather. Comes with two leather straps to attach items like a jacket etc on the lid.
Probably the best haversack I've ever seen in design, and build.