Abstract: A collapsible, quickly deployable floating boom barrier comprises an elongated curtain-like partition of strong, flexible, impervious material supported in a substantially vertical position in the water by a plurality of outrigger-type flotation units spaced along the partition.The partition is in the form of an elongated, flexible belt which has a smooth surface on the side opposite the flotation units, and the smooth side surface engages the material to be contained by the barrier.The barrier has sufficient longitudinal flexibility to encircle an oil spill or a ship that might be unloading or loading oil, and the outrigger flotation units support the partition or belt at a height above the surface of the water which is approximately 1/3 to 1/2 of the partition width.Each outrigger flotation unit comprises a frame and a float.