Abstract: An oil containment boom capable of maintaining a generally vertical orientation in water is disclosed. The containment boom includes a longitudinally extending curtain maintained vertically in the water by floats positioned in pairs in opposed relation along each side of the curtain. The floats are attached by a tether which extends through an opening in the curtain. The tether is capable of reciprocating motion through the opening in the curtain, which allows the floats of each pair to maintain positions in the water which are vertically offset from each other. When the water level on one side of the curtain is higher than on the other side, the float on the high water side rises to a higher position than the float on the opposite side and tends to pull the curtain back into a vertical orientation. The curtain may also include a weight along its lower edge. The self-righting feature of the present oil boom helps to prevent contaminants from washing over the top of the boom in rough areas.