An insulated vessel (10, 100, 130) is provided which is adapted to receive a low or high temperature material to be insulated from the environment. The vessel comprises inner and outer membranes (20, 110, 140) and (30, 120, 150) and an outer casing (40, 170). The inner membrane defines an inner cavity for receiving the low or high temperature material and has a first portion which defines an entrance into the inner membrane. The outer membrane encases the inner membrane such that a space is defined between the inner and outer membranes. The outer membrane includes a second portion which is positioned adjacent to the first portion. An insulating material (60, 160) is located in the space between the inner and outer membranes. The inner and outer membranes are joined together so as to seal off the space from the environment. The space is evacuated to less than atmospheric pressure. The outer casing surrounds the outer membrane and has sufficient strength to provide structural and abuse integrity to the vessel.