Medium- this bag will hold all your essentials plus extras like gloves, hat, drink, etc. Holds approx. 19 litres before being squashed and rolled down.

Large rucksack- this will hold all the above and more bulkier stuff like spare clothes and wetsuit. Holds approx.26 litres before being squashed and top rolled down.

 Extra Large- the 'Ultimate' size, this rucksack holds all the essentials including a dry robe and wetsuit. This bag holds approx. 45 litres before squashed and top rolled down.