No matter how much time you spend at your deepest depth, assume that the entire dive was spent at that depth. For example, if you spend 5 minutes at 90 feet, then ascend to 40 feet for 20 minutes, the dive should be considered a 90-foot dive.

Table 1 lists depths in 10-foot increments, and does not contain rows for depths shallower than 40 feet. If your depth is not listed in the table, round the depth up to the next greater depth. Additionally, all dives shallower than 40 feet are considered to be 40-foot dives. The same is true for dive times. If your exact dive time is not listed in a row, round it up to the next time listed.

A slow ascent allows the body to offgas nitrogen before you reach the surface, and significantly reduces the risk of decompression sickness.

While this precautionary decompression stop is not mandatory, it reduces your risk of developing decompression sickness.