 When no stop depth or time limits are exceeded the diver must decompress more extensively than allowed for in the recommended maximum ascent rate to reduce the risk of decompression sickness.This is conventionally done as decompression stops, which are pauses in ascent at specified depths for specified times derived from the decompression algorithm and based on the dive profile history and breathing gas composition.Depth and duration of obligatory decompression stops are specified by the decompression model used.