Abstract: A mine has a flexible casing which can be fabricated in much the same way at a tubeless tire of modern construction is made. The mine case when uninflated is flexible and capable of being folded into a considerably smaller space than that occupied by a rigid case thus facilitating ease of shipment, but when loaded and inflated it is rigid. Being a collapsible vessel, however, the flexible mine case loses its identity as a straight cylindrical form when planted underwater, and becomes hard to distinguish from rocks, sponge, coral, or other bottom or sea growths.