Abstract: The invention is a flexible portable container for leaking oil tanks which is designed to stop oil spills at their source by preventing the oil from entering the water. The invention in its preferred construction consists of flexible plastic sheets heat-sealed into a shape and size somewhat larger than the oil tank in which it will be used, except for very large tanks, in which multiple units of the invention are used. The top opening is provided with radiating expansion tubes attached to the perimeter of the opening with side arms reaching the adjoining tube. These tubes are inflated by the compressed gas or air compressor to which they are connected. They force the perimeter of said opening against the walls at the bottom of said tank. Built-in flotation tubes around said opening are then inflated to raise said opening to the surface of the liquid, thereby enclosing, except for said top, the remaining contents of said tank.