We are 50 kilometers off the coast of San Diego in late February, holding station in 1,000 meters of water. Onboard our research vessel, the RV Sally Ride, are eight containers, each as large as a compact car, filled with sediment dredged from the deep Pacific Ocean floor. This morning we mixed the sediment with seawater in a huge tank, and over an hour we pumped the entire contents through a wide discharge hose that extended 60 meters down into the water from the side of the ship.