In response to the massive Deepwater Horizon oil spill in the Gulf of Mexico, scientists from the operational response agencies, the academic community, and the private sector employed the oil spill detection technologies and ocean-observing and modeling resources to map the discharged hydrocarbons and simulated their transport with the aim of aiding mitigation efforts. Numerous types of instruments and sensors were used, many numerical models were applied, and a broad array of scientists were involved. These studies represent a new generation of applied oceanography with a focus on a historical oil spill. Preliminary research results reported in 21 chapters of this book are categorized and summarized.