NOAA's research vessel Gordon Gunter is headed toward the site of the oil leak to help investigate a key question: How much oil is spreading under water? The 68-meter-long fisheries research vessel departed Pascagoula, Mississippi, today. Sixteen scientists onboard will try to detect plumes with the ship's sonar and hydrophone. They also have a 450-kilogram autonomous underwater vehicle, loaned from the Monterey Bay Aquarium Research Institute, that can collect up to 10 water samples per trip. The expedition is expected to last 8 days.