complex decompression procedures are necessary. Decompression may follow a pre-planned series of ascents interrupted by stops at specific depths, or may be monitored by a personal decompression computer. Post-dive procedures These include debriefing where appropriate, and equipment maintenance, to ensure that the equipment is kept in good condition for later use. It is also considered a best practice to log each dive upon completion. This is done for several reasons: If a diver is planning on doing multiple dives in a day, they need to know what the depth and duration of previous dives were in order to calculate residual inert gas levels in preparation for the next dive. It is helpful to note what equipment was used for each dive and what the conditions were like for reference when planning another similar dive. For example, the thickness and type of wetsuit used during a dive, and if it was in fresh or salt water, will influence the amount of weight needed. Knowing this information and taking note of whether the weight used was too heavy or too light can help when planning another dive in similar conditions. In order to achieve a level of certification the diver may be required to present evidence of a specified number of logged and verified dives. Professional divers may be legally required to log specific information for every working dive. When a personal dive computer is used, it will accurately record the details of the dive profile, and this data can usually be downloaded to an electronic logbook, in which the diver can add the other details manually. Buddy, team or solo diving Buddy and team diving procedures are intended to ensure that a recreational scuba diver who gets into difficulty underwater is in the presence of a similarly equipped person who will understand the problem and can render assistance. Divers are trained to assist in those emergencies specified in the training standards for their certification, and are required to demonstrate competence in a set of prescribed buddy assistance skills. The fundamentals of buddy and team safety are centred on diver communication, redundancy of gear and breathing gas by sharing with the buddy, and the added situational perspective of another diver. There is general consensus that the presence of a buddy both willing and competent to assist can reduce the risk of certain classes of accidents, but much less agreement on how often