 A simple record of depth and time for a dive is useful as a legal record of a diving operation, where this is required, and in the case of an accident during the dive, an accurately recorded dive profile can provide useful diagnostic information for treatment of the injured diver and for analysis of the circumstances leading to the accident and the action taken during and after the incident.A proposed dive profile is necessary for effective dive planning, both for estimating the required breathing gas composition and quantities, for planning decompression, and for choosing suitable diving equipment and other logistical aspects.The breathing gas mixtures appropriate to a dive depend to a large extent on the maximum depth and the decompression obligations incurred by the planned duration of the dive and the time spent at each depth.