Have you ever wondered about the importance of taking breaks while scuba diving? Well, let me introduce you to the concept of a surface interval. A surface interval is a designated period of time that divers must spend on the surface between consecutive dives. It allows the body to off-gas the excess nitrogen absorbed during the previous dive, ensuring a safe ascent and reducing the risk of decompression sickness. So, let’s dive into the world of surface intervals and discover why they play a crucial role in the scuba diving experience.

Table of Contents

Definition of Surface Interval

Introduction to surface interval

A surface interval in scuba diving refers to the period of time that a diver spends at the surface between consecutive dives. It is a critical component of safe diving practices as it allows the body to off-gas nitrogen, reduces the risk of decompression sickness, and allows the diver to rest and recharge before the next dive.

Duration of a surface interval

The duration of a surface interval varies depending on several factors such as the depth and duration of the previous dive, the dive profile, and the diver’s personal fitness and age. As a general guideline, a surface interval of at least one hour is recommended for recreational divers, while technical divers may require longer intervals.

Purpose of a surface interval

The main purpose of a surface interval is to allow the body to eliminate excess nitrogen absorbed during a dive. When diving, the body takes in nitrogen from the compressed air in the scuba tank. During the ascent, the decreasing pressure causes the nitrogen to dissolve in the tissues. A surface interval provides time for the nitrogen to off-gas through respiration, reducing the risk of decompression sickness.

Importance of Surface Interval

Effects of diving on the body

Diving puts the body under unique physiological stress. As you descend, the increasing pressure affects various body systems, including the respiratory and circulatory systems. The body absorbs nitrogen from the breathing gas, which can lead to nitrogen saturation in the tissues. Without a surface interval, these excess nitrogen bubbles can cause decompression sickness, which can range from mild symptoms to life-threatening conditions.

Allowing nitrogen off-gassing

During a surface interval, the body has a chance to eliminate the excess nitrogen absorbed during the dive. As you breathe in fresh air at the surface, the higher oxygen levels facilitate the off-gassing process. The body slowly releases the dissolved nitrogen through respiration, allowing it to escape without causing harm. A sufficient surface interval gives the body ample time to eliminate the accumulated nitrogen, minimizing the risk of decompression sickness.

Preventing decompression sickness

Decompression sickness occurs when nitrogen bubbles formed during a dive don’t have enough time to off-gas and accumulate in the body’s tissues. These bubbles can cause a variety of symptoms, including joint pain, dizziness, and even paralysis or death in severe cases. A proper surface interval, along with adherence to dive tables or dive computer guidelines, helps prevent decompression sickness by allowing the body to safely eliminate the excess nitrogen absorbed during the dive.

Activities During Surface Interval

Resting and relaxation

One of the primary purposes of a surface interval is to allow the diver to rest and recover energy before the next dive. After a dive, the body may experience physical fatigue, especially if it was a strenuous or deep dive. Taking the time to relax and recharge during the surface interval helps ensure that you are mentally and physically prepared for the upcoming dive.

Hydration and nutrition

Staying properly hydrated and nourished during a surface interval is crucial for maintaining optimal diving performance. Diving can be physically demanding and can cause dehydration. Drinking water or an electrolyte-rich beverage and consuming nutritious snacks or meals during the surface interval replenishes energy levels and supports overall well-being.

Planning for the next dive

The surface interval is an ideal time to plan for the next dive. Divers can discuss the dive site, review the dive plan, and check for any changes in conditions or weather. It is also an opportunity to adjust dive equipment, such as changing batteries or checking dive computer settings, to ensure everything is in proper working condition.

Equipment checks and adjustments

During the surface interval, it is essential to inspect and maintain diving equipment. This includes checking the condition and functionality of the scuba tanks, regulators, BCDs (buoyancy control devices), and other gear. Any necessary adjustments or repairs can be made during this time to ensure a safe and enjoyable dive experience.

Surface interval safety guidelines

It is crucial to follow safety guidelines during the surface interval to minimize risks and ensure a safe return to diving. These guidelines may include avoiding excessive sun exposure, staying away from activities that can cause overheating or exhaustion, and adhering to any specific recommendations from the dive instructor or dive center.

Factors Affecting Surface Interval

Dive profile and dive computer readings

The dive profile, including the depth and duration of the previous dive, plays a significant role in determining the necessary surface interval. Deeper and longer dives generally require longer surface intervals to allow for sufficient off-gassing. Dive computer readings can provide valuable information regarding the accumulated nitrogen levels and recommended surface interval duration.

Depth and duration of previous dive

Deeper dives and longer bottom times increase the absorption of nitrogen and the need for a longer surface interval. The body requires more time to eliminate the excess nitrogen accumulated during extended or deep dives. It is essential to carefully consider these factors when planning the duration of the surface interval to promote safe diving practices.

Altitude and multiple dives

Altitude can significantly affect the required surface interval. When diving at high altitudes, the decreased atmospheric pressure causes the body to off-gas nitrogen more rapidly. As a result, shorter surface intervals may be sufficient compared to diving at sea level. Additionally, multiple dives in a day require longer surface intervals to ensure adequate off-gassing and reduce the risk of nitrogen bubbles forming in the body.

Personal fitness and age

Individual factors such as personal fitness and age can influence the body’s ability to off-gas nitrogen efficiently. Fitness levels and overall health can affect respiration and circulation, impacting the off-gassing process. Older divers may require longer surface intervals due to decreased physiological efficiency. It is crucial to take these factors into account when determining the appropriate surface interval duration.

Environmental conditions

Environmental factors such as water temperature, currents, and visibility can also affect the necessary surface interval. Cold water may increase the risk of hypothermia, requiring additional time for rest and warming up. Strong currents or poor visibility can increase physical exertion during the dive, necessitating longer surface intervals for recovery.

Surface Interval vs. Decompression Stops

Difference between surface interval and decompression stops

A surface interval and a decompression stop serve different purposes during diving. A surface interval occurs between consecutive dives and allows the body to off-gas nitrogen absorbed during the previous dive. It is a period of rest, recovery, and time for the body to eliminate excess nitrogen. On the other hand, a decompression stop is a specific duration spent at a specific depth during the ascent from a dive to safely off-gas nitrogen bubbles formed during the dive. Decompression stops are typically required for deep or extended dives to prevent decompression sickness.

Purpose and methods of decompression stops

The purpose of a decompression stop is to gradually release the accumulated nitrogen gas bubbles from the tissues, allowing them to off-gas safely. Decompression stops are based on dive tables or calculated by dive computers, taking into account the diver’s depth and bottom time. During a decompression stop, the diver remains at a shallower depth for a specified amount of time, allowing the body to off-gas nitrogen without experiencing decompression sickness.

Sequential dives and multiple decompression stops

When performing sequential dives or multiple dives in a day, each dive’s surface interval is crucial for off-gassing nitrogen from the previous dive. The accumulated nitrogen is off-gassed during the surface interval, while decompression stops are specific to releasing nitrogen bubbles formed during a particular dive. Proper planning and adherence to surface interval and decompression stop guidelines help prevent decompression sickness when engaging in multiple dives.

Tips for Maximizing Surface Interval

Staying warm and comfortable

During the surface interval, it is essential to stay warm and comfortable. Dry off and change into dry clothing to avoid feeling chilled. Use blankets or towels for insulation if needed. Adequate warmth helps relax the body and promotes efficient off-gassing.

Proper hydration and nutrition

Maintaining proper hydration and nutrition during the surface interval is key to optimizing diving performance. Drink water or an electrolyte-rich beverage to replenish fluids lost during the dive. Consume nutritious snacks or meals to provide energy for the next dive and support the body’s recovery process.

Breathing techniques and relaxation

Engaging in breathing techniques and relaxation exercises during the surface interval can help enhance off-gassing and mental well-being. Deep breathing and controlled exhalation enable the body to eliminate nitrogen more efficiently. Relaxation techniques, such as meditation or visualization, help calm the mind and reduce stress between dives.

Avoiding alcohol and excessive exertion

Alcohol and excessive exertion should be avoided during the surface interval. Alcohol can impair judgment and increase dehydration, while excessive physical exertion may lead to fatigue and impact diving performance. Opting for non-alcoholic beverages and engaging in light activities or gentle stretching promotes a more enjoyable and safe diving experience.

Monitoring the time and avoiding delays

Keeping track of the surface interval time is crucial to ensure adherence to safety guidelines and avoid potential risks. Use a reliable timepiece or dive computer to monitor the duration of the surface interval accurately. Avoid unnecessary delays or distractions that may result in an insufficient surface interval, as this can increase the risk of decompression sickness.

Common Surface Interval Questions

Can you ascend during a surface interval?

During a surface interval, divers are encouraged to remain at the surface and not descend. Ascending during a surface interval can interrupt the off-gassing process and increase the risk of decompression sickness. It is important to use the surface interval as an opportunity for rest and recovery before the next dive.

What should you do in case of an emergency?

In case of an emergency during the surface interval, divers should follow the standard emergency response protocols. This may include providing immediate assistance to an injured diver, notifying the dive leader or dive center, and activating emergency procedures. Having a designated emergency plan in place and ensuring all divers are familiar with it is crucial for maintaining a safe diving environment.

How does the surface interval affect no-decompression limits?

The surface interval plays a vital role in determining the no-decompression limits for subsequent dives. During the surface interval, the body eliminates excess nitrogen absorbed during the previous dive, allowing for safer subsequent dives within the no-decompression limits. The duration of the surface interval directly affects the body’s off-gassing capability and, therefore, the allowable bottom time and depth for subsequent dives.

Can you engage in other water activities during a surface interval?

While it is generally recommended to rest and relax during the surface interval, engaging in other water activities may be permissible depending on the specific circumstances. Some divers may choose to snorkel or swim at the surface, as long as it does not interfere with the off-gassing process or pose additional risks. However, it is crucial to exercise caution, maintain proper supervision, and avoid excessive physical exertion during these activities.

What are the signs of nitrogen narcosis during a surface interval?

Nitrogen narcosis, also known as “rapture of the deep,” is a condition that can occur at depths beyond recreational diving limits. During a surface interval, nitrogen narcosis is typically not a concern as the diver is at the surface. However, if nitrogen narcosis symptoms were experienced during the previous dive, such as a feeling of intoxication, impaired judgment, or disorientation, it is essential to recognize these signs and inform the dive leader or instructor for appropriate actions.

Surface Interval Guidelines for Dive Professionals

Educating divers about surface interval

Dive professionals play a crucial role in educating and informing divers about the importance of the surface interval. They should provide detailed explanations of the purpose, duration, and effects of a surface interval, as well as the potential risks associated with insufficient surface intervals. Clear communication ensures divers understand the importance of adhering to recommended surface interval guidelines.

Monitoring and enforcing surface interval times

Dive professionals should monitor and enforce surface interval times to maintain the safety of divers. This involves ensuring that divers take the necessary time between dives to off-gas nitrogen and rest adequately. Dive leaders or instructors can use dive tables, dive computers, or other tools to track and enforce appropriate surface interval durations.

Guidance for planning multiple dives in a day

Dive professionals are responsible for providing guidance on planning multiple dives in a day. This involves calculating appropriate surface intervals based on the dive profiles, ensuring divers have sufficient time to off-gas nitrogen, and preventing decompression sickness. Dive professionals should also consider factors such as dive site conditions, diver experience, and personal fitness levels when helping plan multiple dives.

Recognizing and managing signs of nitrogen narcosis

Dive professionals should be able to recognize and manage signs of nitrogen narcosis during the surface interval or any other dive. Training and experience enable them to identify symptoms such as impaired judgment, euphoria, or confusion. If such signs are observed, dive professionals must take appropriate actions, such as closely monitoring the diver, ensuring safety, and potentially adjusting the dive plan.

Emergency response protocols during surface interval

Dive professionals should establish emergency response protocols specifically for surface interval situations. This includes having emergency contact information readily available, ensuring appropriate first aid and rescue equipment are accessible, and providing specific directions for responding to emergencies during the surface interval. Prompt and effective emergency response protocols during the surface interval contribute to maintaining a safe diving environment.

Case Studies: Surface Interval Scenarios

Scenario 1: Single Dive with Short Surface Interval

In this scenario, a diver completes a single, relatively shallow dive and only takes a short surface interval of 30 minutes before starting the next dive. Due to the shallow depth and short bottom time, the amount of nitrogen absorbed is relatively low, allowing for a shorter surface interval. However, it is important to note that the recommended surface interval is generally a minimum of one hour, and longer intervals are recommended for most dives.

Scenario 2: Multiple Dives with Optimal Surface Interval

In this scenario, a group of divers plans to conduct multiple dives in a day. They adhere to the recommended surface interval guidelines and allow sufficient time for off-gassing between each dive. By planning and following appropriate surface intervals, they minimize the risk of decompression sickness and ensure the safety of all divers. The duration of the surface interval is determined based on the dive profiles, dive computer readings, and the specific needs of each diver.

Scenario 3: Emergency Surface Interval due to Equipment Failure

In this scenario, a diver experiences a malfunction with their scuba equipment during a dive, requiring an emergency ascent. As a result, the diver must spend an extended period of time on the surface before re-entering the water. This unplanned surface interval allows for unplanned nitrogen off-gassing, and dive professionals should closely monitor the diver for any signs of decompression sickness or other complications.

Scenario 4: Extended Surface Interval with Alternate Activities

In this scenario, a group of divers decides to take an extended surface interval of several hours between dives. During this time, they engage in other water-based activities, such as snorkeling or swimming. While they are enjoying their time at the surface, it is important for the divers to ensure that they do not exert themselves excessively and interfere with the off-gassing process. They should also monitor the time and gradually increase their activities to avoid delays and adhere to the recommended surface interval duration.

Scenario 5: Surface Interval at High Altitude

In this scenario, divers plan a dive at a high-altitude location, such as a mountain lake. Due to the reduced atmospheric pressure at higher altitudes, the necessary surface interval duration may be shorter compared to diving at sea level. Dive professionals should provide specific guidelines for surface interval duration in such environments to ensure divers off-gas nitrogen effectively and minimize the risk of decompression sickness.


The importance of a surface interval in scuba diving cannot be overstated. It provides the body with the necessary time to off-gas nitrogen, rest, and recharge, reducing the risk of decompression sickness. Proper planning, adherence to recommended surface interval guidelines, and monitoring individual factors contribute to safe and enjoyable diving experiences. By understanding the purpose of the surface interval, following safety guidelines, and maximizing its benefits through appropriate activities and precautions, divers can ensure a safer and more rewarding underwater adventure.