 A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool.Deep sea food webs are complex, and aspects of the system are poorly understood.Typically, predator-prey interactions within the deep are compiled by direct observation (likely from remotely operated underwater vehicles), analysis of stomach contents, and biochemical analysis.