 Wet environments, whether on land in the form of peat bogs and wells, or underwater are particularly important for the survival of organic material, such as wood, leather, fabric and horn.Cold and absence of light also aid survival of artifacts, because there is little energy available for either organic activity or chemical reactions.Salt water provides for greater organic activity than freshwater, and in particular, the shipworm, terredo navalis, lives only in salt water, so some of the best preservation in the absence of sediments has been found in the cold, dark waters of the Great Lakes in North America and in the (low salinity) Baltic Sea (where "Vasa" was preserved).