 The perception is that these reefs are less vulnerable than tropical reefs and the sessile species are less vulnerable to diver impact.Diver contact with the bottom is also prevalent on temperate reefs – one of the main forms mentioned is fin contact with the bottom sediment, raising particulate material into the water column and degrading visibility.The impact of recreational scuba diving on recreational dive values and the cultural heritage of shipwrecks has been found to comprise four basic types