 The quantity of gases required for scuba will depend on the time spent at each depth, the breathing rate of the diver, the type of breathing apparatus to be used, and reasonable allowances for contingencies.For planning and monitoring of inert gas absorption using decompression tables, the data usually consists of the maximum depth reached during the dive, the bottom time as defined by the dive table in use and the length of time underwater (total dive time).For repetitive dives it also includes the "surface interval" – the time spent above the water between the previous dive and the start of the next dive.