The British Army Other Arms PLCE Bergen Rucksack is a a super design that are a good size approx. 70 litre
These are the rucksack of choice for those on a budget or not needing the extra 30 litres capacity the Infantry type offer, generally they are in excellent condition etc and also have external carrying straps comparable to that of a suitcase or a briefcase
Personally myself when using these on regular trips I would encourage the use of lightweight dry bags in their various capacities (also in varying colours!) to keep kit separate and identifiable, from keeping wet and dry stuff separate to clean and dirty washing as well as clothes, shoes and other equipment!
These rucksacks are also known as the Engineers Bergen
The bag has a double ended strong zip access for ease of getting in and out 2 large padded adjustable Shoulder Straps for taking the strain of added weight.
The bag has for clips on either side to attach the PLCE day packs if required or Camelbaks or another other PLCE clip-on or zip-on option or alternative including medical packs.
The straps can be covered up by a roll down DPM Cover which seals with velcro so there are no straps to catch, bag can the be carried by tough handle on the top.