In open-water marine spills, the primary response objectives are:
- To prevent the spill from reaching shore,
- To reduce the impact on marine life, and
- To speed the degradation of any unrecovered oil.
Weather permitting, booms can be used to contain or divert the spilled oil, which may then be recovered using skimmers or burned off. However, if winds or waves are too high, booms will be ineffective and will not provide adequate containment of the spill.
Dispersants, applied to the spill via aircraft, can be effective in breaking up spills of light- or medium-density oils. Dispersant use is also contingent upon weather, as high winds make it difficult to accurately target the spill from the air. Sorbents may be used for small-volume spills, or as a final "polish" after other response options have been used.
Dispersants are chemical agents (similar to soaps and detergents) that help break up an oil slick into very small droplets, which dilute throughout the water. While this does not remove the spilled material, smaller oil particles are more easily biodegraded and it provides a measure of protection for sensitive habitats threatened by a surface slick. Dispersants are sprayed onto spills by specially equipped boats or planes.