Part 6 of a 6-part series describing WHOI's efforts to understand the scope and impact of the Deepwater Horizon oil spill in the Gulf of Mexico. "Assessing the Impacts" describes a range of work by WHOI scientists in the months after the spill. Research included tracking potential biological impacts in the Gulf, developing new methods to measure dispersants in the water, and a trip by scientists aboard the submersible Alvin and autonomous underwater vehicle Sentry to survey deep-water coral communities near the site of the ruptured well.