Disclosed is a pouch (also called a flexible container) for holding fluid, the pouch including: (a) a first polymeric sheet including a first inner body and a first outer surface, the first inner body including a first inner surface and inner microstructure extending from the first inner surface, the first inner body defining an aerial microstructure surface area density (AMSAD) between 5% and 15%； (b) a second polymeric sheet including a second inner surface and a second outer surface. The second polymeric sheet may be joined with the first polymeric sheet such that the first inner body and the second inner surface form an air-tight fluid chamber therebetween. The second polymeric sheet may lack microstructure extending from the second inner surface. The first inner surface, the first outer surface, the second inner surface, and the second outer surface may be smooth and non-recessed.
