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Scuba diving is a magnificent journey into the unseen, serene world underwater, allowing divers to explore the mystique of aquatic life. When embarking on this adventure, meticulous dive planning is imperative, particularly when using enriched air nitrox (EANx) to ensure safety and optimize the diving experience. Nitrox diving is renowned for its ability to extend bottom times and reduce decompression stops, granting divers extended interaction with the subaquatic realm.

Understanding Nitrox

Nitrox refers to any gas mixture composed of nitrogen and oxygen; in diving, the term is typically used to describe mixtures with an oxygen concentration higher than 21%, the proportion in regular air. Nitrox mixtures are primarily used to minimize the nitrogen absorption in the body, effectively reducing the risk of decompression sickness and allowing for longer, safer dives.

Maximum Operating Depth (MOD) and its Importance

One of the crucial considerations when planning a dive with nitrox is to determine the Maximum Operating Depth (MOD). MOD is the deepest depth a diver can safely reach with a specific nitrox mix, limiting the partial pressure of oxygen (PPO2) to a maximum of 1.4 atmospheres. Exceeding the MOD can lead to oxygen toxicity, a serious condition that requires immediate attention.

Calculating the MOD is essential for diver safety. It is computed using the formula:

Choosing the Best Gas Mix

The best nitrox mixture depends on the dive profile, including the planned depth and bottom time. Common nitrox mixes are EANx32 and EANx36, with 32% and 36% oxygen, respectively.

  1. EANx32: This mixture is versatile and suitable for a range of recreational dive profiles. It offers longer no-decompression limits compared to air and is ideal for depths up to around 33 meters.
  2. EANx36: Best for relatively shallower dives, EANx36 allows for even less nitrogen absorption and longer bottom times, but the MOD is limited to approximately 29 meters.

Dive Planning Steps with Nitrox

  1. Define Dive Objectives: Clearly outline your dive goals, including desired depth, time, and areas to explore.
  2. Select Appropriate Nitrox Mix: Based on your objectives, choose a nitrox mix that maximizes bottom time while maintaining safety. Use a nitrox table or dive computer to find the suitable mix.
  3. Calculate MOD and PPO2: Compute the MOD for your chosen mix and ensure that your planned depth does not exceed the MOD.
  4. Analyze the Cylinder Contents: Prior to diving, use an oxygen analyzer to confirm the oxygen percentage in your cylinder and ensure it aligns with your dive plan.
  5. Plan Your Dive and Dive Your Plan: Establish a clear dive plan, including entry and exit points, navigation, and emergency procedures, and adhere strictly to it.
  6. Monitor Your Dive: Continuously monitor your depth, time, and air consumption during the dive. Regularly check your dive computer to avoid exceeding planned limits and ensure a safe ascent rate.
Nitrox diving: dive planning for mod and best gas mix

Enhance your Dive Exploration

Dive planning with nitrox is indispensable for divers keen on exploring deeper or staying submerged longer. The optimal use of nitrox mixtures such as EANx32 and EANx36 ensures that divers not only experience extended bottom times but also encounter lesser nitrogen absorption, significantly reducing the risk of decompression sickness.

By carefully selecting nitrox mixes and rigorously adhering to dive plans, divers can seamlessly blend safety with unparalleled underwater exploration, making each dive a more enriched and fulfilling experience.


Dive planning with nitrox is an essential skill for all scuba divers, allowing them to explore the beauty and mysteries of the underwater world more safely and for extended periods. By understanding the importance of MOD and choosing the best nitrox mixture for the dive profile, divers can ensure a safer and more enjoyable experience as they plunge into the ocean’s depths to uncover its hidden treasures. Whether you are a novice diver or an experienced underwater explorer, effective dive planning with nitrox will undoubtedly enhance your diving adventures.

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