The depletion of terrestrial global oil reserves has shifted oil exploration into offshore and ultra-deep water oil reserves to meet global energy demands. The explosion aboard the Deepwater Horizon in April 2010 resulted in an estimated total release of ~5 million barrels of light, sweet crude oil into the Gulf of Mexico and shifted attention toward the environmental risks associated with offshore oil production. The growing emphasis on deep water and ultra-deep water oil production poses a significant environmental threat. Every oil spill is unique. The molecular transformations that occur to petroleum after contact with seawater depend on the physical and chemical properties of the spilled oil, environmental conditions, and deposition environment. Knowing this helps researchers understand how it will break down, where it came from, and what impact it will have on the environment.