The Stillwater Twin Pocket Lined Carryall is a superb option for transporting all your gear to the bank. With generous sized pockets, in addition to the main bag, there's plenty of room for everything you need at the bankside.
Dimensions (excluding pockets):
Medium: (W)50cm x (D)27 x (H)29cm
Large: (W)50cm (D)36cm x (H)35cm