Kingston Images

Marine archaeologists use a underwater dredge to move sediments off what they believe is a 16th century anchor from Hernan Cortes scuttled fleet in the Gulf of Mexico. The dredge acts like a giant vacuum cleaner creating suction by sucking water in from the surface and forcing it down a long tube to the bottom of the ocean where a venturi effect creates suction. In the photo, a engine attached to the yellow hose is forcing water down from the surface and the blue hose is moving sediments away from the excavation site. Photo by, Jonathan Kingston/National Geographic Creative