This note illustrates the structure of a wall for a container fit for standing high external pressure, as the wall has cavities filled with fluid at a very high pressure. It relates the results, which seem encouraging, of experiments both on metal patterns, tested in a pressure tank, and on patterns made of photoplastic material. The latter experiments have been carried out at the University of Pisa, under the control of Prof. C. Raymondi. This system is amply covered by patent in Italy as well as abroad.