Marine sediment collection for the assessment of grain size and total organic matter must be carried out avoiding any manipulation of the sample that could affect the vertical stratication of the sediment or a relevant alteration of the in situ physical-chemical properties of the surface layer (e.g., resuspension, warming, desiccation). A ship and special equipment are requested for sediment sampling at deeper depths. Common devices are grabs, box corers, and multiple corers (Figure 1.1). Nonetheless, the use of box corers or multiple corers is preferable. Multiple corers, moreover, are equipped with transparent Plexiglas® (Rohm & Haas Company, Philadelphia, PA) liners that permit analysis of sample quality and integrity immediately after retrieval and measurement of the depth of the redox potential discontinuity (RPD) layer. The reduced velocity of sediment penetration of multiple corer liners allows collection of a totally undisturbed sediment sample.