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What is Ascent when Diving?

Ascent refers to the part of a dive profile during which a diver moves upwards towards the surface, marking the transition from being submerged to resurfacing. It is a critical component of scuba diving as it directly influences a diver’s safety and well-being. An ascent is not always a continuous, uninterrupted process; it may include planned stops, such as decompression stops, to facilitate safe decompression and avoid the risk of decompression sickness, commonly known as “the bends.” This entry will discuss the importance of ascent in scuba diving, its stages, and best practices to ensure a safe and enjoyable diving experience.

Importance of Ascent in Scuba Diving

Ascent is a vital aspect of scuba diving because it directly affects a diver’s safety. When a diver descends, they are subjected to increasing pressure as the depth increases. This pressure causes nitrogen, a component of the air we breathe, to dissolve in the diver’s tissues. As a diver ascends, the surrounding pressure decreases, and the nitrogen gas starts to come out of the tissues. Rapid ascent may cause the nitrogen to form bubbles within the body, leading to decompression sickness, a potentially severe and life-threatening condition. Therefore, it is crucial to follow proper ascent procedures to ensure a safe and controlled release of nitrogen from the body.

Stages of Ascent

Initial ascent

The initial ascent begins when the diver decides to end the dive and starts moving upwards from the bottom or the maximum depth reached during the dive. This stage requires the diver to maintain neutral buoyancy and adjust their buoyancy compensator (BC) as needed.

Ascent with stops

This stage may include several stops at different depths, depending on the dive profile and the need for decompression. These stops help regulate the release of nitrogen from the body, ensuring a safe ascent. A dive computer or dive tables can help determine the appropriate decompression stops and durations.

Final ascent

The final ascent is the last stage of ascent, typically starting from the shallowest decompression stop or safety stop. This stage requires the diver to ascend slowly and maintain a controlled rate, usually not exceeding 30 feet (9 meters) per minute. The final ascent concludes when the diver reaches the surface and inflates their BC to achieve positive buoyancy.

Best Practices for a Safe Ascent

Controlled ascent rate

A critical aspect of a safe ascent is maintaining a controlled ascent rate. The recommended ascent rate varies depending on the diver’s depth, dive profile, and personal factors. Generally, an ascent rate of 30 feet (9 meters) per minute is considered safe, but some agencies recommend a slower ascent rate of 18 feet (5.5 meters) per minute for the final 60 feet (18 meters) to the surface.

Decompression stops

Divers should adhere to the decompression stops determined by their dive computer or dive tables. These stops allow the body to eliminate nitrogen at a safe rate, reducing the risk of decompression sickness.

Safety stop

A safety stop is a precautionary measure, usually conducted at a depth of 15 feet (4.5 meters) for 3-5 minutes. This stop helps reduce residual nitrogen in the body, especially after deeper or longer dives.

Use of visual and auditory cues

Monitoring depth and ascent rate can be facilitated through the use of visual and auditory cues, such as dive computers or depth gauges, and by observing changes in the color and intensity of natural light.

Equalizing ear pressure

As pressure changes during ascent, it is essential to equalize ear pressure frequently. Divers can do this by performing the Valsalva maneuver or other equalization techniques, such as swallowing or yawning, to help open the Eustachian tubes and equalize the pressure between the middle ear and the surrounding environment.

Buddy system

Diving with a buddy ensures that both divers can monitor and assist each other during ascent, reducing the risk of accidents. Communication through hand signals or underwater slates can help divers stay informed about each other’s status and any issues that may arise.

Maintaining buoyancy control

Proper buoyancy control is essential during ascent to avoid rapid, uncontrolled ascents or descents. Divers should adjust their buoyancy compensator as needed to maintain neutral buoyancy throughout the ascent.

Monitoring air supply

Divers should keep a close eye on their air supply during ascent to ensure they have enough air to complete the ascent and any required decompression stops safely. Running out of air during ascent can lead to panic, rapid ascent, and increased risk of decompression sickness.

Preparing for surface conditions

As the diver approaches the surface, it is essential to be aware of surface conditions, such as waves, boat traffic, or weather changes. Divers should inflate their surface marker buoy (SMB) to signal their position to boats and be prepared to handle any surface conditions they may encounter upon surfacing.

Risks and Complications During Ascent

Decompression sickness

Decompression sickness occurs when nitrogen bubbles form in the body due to a rapid ascent, causing pain, neurological symptoms, or even death. Adhering to proper ascent rates, decompression stops, and safety stops can minimize this risk.


Barotrauma refers to injuries caused by changes in pressure, such as ear or sinus injuries. Equalizing ear pressure and ascending slowly can help reduce the risk of barotrauma.

Pulmonary overexpansion injury

Holding one’s breath during ascent can cause the lungs to overexpand, potentially resulting in a lung overexpansion injury, such as pneumothorax or arterial gas embolism. Breathing continuously and avoiding breath-holding during ascent can minimize this risk.

Nitrogen narcosis

Nitrogen narcosis, or “rapture of the deep,” is a temporary altered state of consciousness caused by the effects of nitrogen under pressure. As the diver ascends, the effects of nitrogen narcosis typically subside.

Key Takeaways

In conclusion, the ascent phase in scuba diving is a critical component that directly impacts a diver’s safety and well-being. Following best practices, adhering to proper ascent rates, and completing necessary decompression stops can help ensure a safe and enjoyable diving experience. By understanding the importance of ascent and mastering the techniques and procedures involved, divers can minimize the risks associated with scuba diving and confidently explore the underwater world.