Recommended maximum depth for recreational divers is 30 m/90 ft. The reason for this limit is the increased risk of gas narcosis and decompression sickness. Therefore, diving below 30 m/90 ft until 40 m/120 ft is a special diving activity. This activity requires a specific training. If you are attacked by the depth and you are a PADI Advanced Open Water Diver, you must consider this course. This course will teach you the risks and necessary precautions that should be taken while deep diving and how to enjoy depths with safety and awareness. There are 4 required open water dives to complete this course, so a weekend trip would be enough to finish it. It is a must course if you want to explore the mysteries of depth safely.