Neptune III Full Face Mask: The Complete IDM Guide

A full face dive mask changes the way you experience scuba diving. Instead of holding a regulator mouthpiece between your teeth and breathing only through your mouth, an Integrated Diving Mask covers your eyes, nose and mouth while supplying breathing gas through an integrated second stage. The result is a much more natural-feeling way to breathe underwater — and one that opens up possibilities for communication, cold-water diving and extended comfort.

Among modern IDMs, the Neptune III Full Face Mask takes this concept considerably further. Developed by OCEAN REEF, the Neptune III combines a wide-view visor, integrated regulator, patented air-circulation system, 3D equalisation system, surface air valve and six-strap harness into a single diving system. It is designed around one simple idea: making breathing underwater feel less like using a piece of equipment and more like simply breathing.

That does not mean an IDM is automatically the right choice for every diver. A full face mask requires proper training, correct fitting and an understanding of the procedures that are different from conventional scuba equipment. But for divers who want the comfort and functionality of an integrated system, the Neptune III is an interesting piece of equipment to understand.

It is worth making one distinction clear: a full face mask is not simply a larger version of a normal dive mask.

With a traditional mask and regulator, you learn to breathe through your mouth around the regulator mouthpiece. With an IDM, the breathing apparatus is integrated into the mask and the air is directed through an internal oral-nasal pocket.

That changes several aspects of diving, including equalisation, emergency procedures, equipment checks and how the mask is donned and removed.

A full face mask therefore needs to be treated as a complete diving system rather than simply another type of mask.

The Neptune III is OCEAN REEF's flagship recreational/professional-style IDM design, built around an integrated vertically positioned, balanced second-stage regulator. The current Neptune III range is also designed to accommodate accessories and communication systems, making the platform relevant beyond straightforward recreational diving.

At the centre of the system is the regulator. Rather than having a conventional second stage hanging from the diver's mouth, the regulator is integrated into the mask and designed specifically for this configuration.

The result is a single piece of equipment incorporating:

• Full-face visor and silicone face seal
• Integrated second-stage regulator
• Oral-nasal breathing pocket
• 3D equalisation system
• Air-circulation system
• Purge button
• Surface air valve
• Six-strap harness
• Quick-release buckle system
• Accessory mounting options
• Communication compatibility

The integrated design is what separates the Neptune III from a conventional mask-and-regulator setup.

One of the first things divers notice when moving to an IDM is the ability to breathe through the nose.

That may sound like a small change, but underwater it can feel surprisingly different. There is no mouthpiece to hold between your teeth, and your mouth is no longer occupied by the second stage.

For some divers, that creates a more relaxed and intuitive breathing experience. It can also be particularly appealing during longer dives where jaw comfort becomes increasingly noticeable.

The Neptune III's oral-nasal pocket separates the breathing area from the rest of the mask interior and uses one-way valves as part of its breathing circulation system. OCEAN REEF says the design helps prevent exhaled air from being mixed back into the fresh breathing supply.

A conventional regulator requires the diver to hold a mouthpiece in place throughout the dive.

That is not usually a problem on a short recreational dive, but some divers experience jaw fatigue during longer dives, repetitive diving or professional work.

Because there is no conventional mouthpiece in the Neptune III, the diver does not have to bite down to keep the second stage in position.

For divers who regularly notice jaw fatigue, this can be one of the most immediately noticeable benefits of an IDM.

Another major attraction of a full face mask is the field of vision.

The Neptune III uses a large transparent polycarbonate visor, with the design intended to provide a broad view while maintaining a relatively compact internal volume. Mike's Dive Store's current Neptune III listing notes that the design provides up to 20% more field of vision than its predecessor, the Neptune II.

That additional visual space can change how diving feels.

Instead of looking through the relatively small viewing area of a traditional low-volume mask, the diver has a much more open view around them. For reef diving, wreck exploration, professional work and underwater photography, that can make the environment feel considerably more immersive.

The visor also uses a siloxane resin coating on both sides, according to OCEAN REEF's technical specifications, for improved scratch and chemical resistance and light transmission.

The large visor is not just about seeing more marine life — it contributes significantly to the overall sense of openness that makes an IDM feel different from conventional scuba equipment.

Fogging is one of those annoyances almost every diver knows.

Traditional masks commonly require some combination of cleaning, preparation and anti-fog treatment to keep condensation under control. An IDM approaches the problem differently.

The Neptune III uses a dedicated air-circulation system around the visor. Fresh breathing gas is directed through the system while the oral-nasal pocket manages the breathing circulation.

OCEAN REEF states that the one-way circulation helps keep the visor clear and prevents exhaled air from being mixed with fresh inhaled air.

That means the Neptune III is designed to minimise fogging through its airflow architecture rather than relying on a conventional mask treatment.

It is one of the most compelling practical differences between an IDM and a standard diving mask.

Equalisation is one of the areas where a full face mask differs most obviously from a traditional setup.

With a conventional mask, you pinch your nose and gently add air to the mask and middle ear as you descend.

The Neptune III incorporates a patented 3D equalisation system. Internal nose plugs can be adjusted in three directions:

1. Up and down
2. Wide and narrow
3. Close and far

When correctly adjusted, the system brings the plugs into position around the diver's nostrils, allowing the diver to equalise while wearing the full face mask.

Correct adjustment is essential because the equalisation system needs to create the appropriate nasal seal for the individual diver.

As with any diving equipment, equalisation should never be forced. If you cannot equalise comfortably, stop the descent and resolve the problem rather than continuing downward.

A common question from divers considering an IDM is what happens if the mask floods.

The Neptune III is designed with one-way directional exhaust and draining valves. Water entering the mask can be removed through the breathing and exhaust system, while pressing the regulator purge button provides a stronger flow of air to help clear water more quickly.

The mask can also be configured with the directional exhaust on the left, right or both sides depending on the setup.

The important point is that flooding does not simply mean removing the entire mask underwater. The system is designed to allow the diver to clear water while maintaining the integrated breathing system.

That said, divers should still be properly trained in IDM emergency procedures before using one in open water.

Another clever feature is the surface air valve.

At the surface, a diver wearing a conventional regulator normally switches to breathing from the regulator or removes their mask if they want to breathe normally.

The Neptune III's surface air valve allows ambient air to enter the mask while the diver remains on the surface.

The valve has large air vents and is designed to be easy to locate and operate.

This is particularly useful during surface intervals, waiting at the surface or preparing for a descent.

For instructors, guides, commercial divers and technical teams, communication can be one of the biggest advantages of an IDM.

Trying to communicate while wearing a conventional regulator generally means hand signals, slates or other signalling systems. An IDM can instead be fitted with compatible underwater communication equipment.

OCEAN REEF offers communication configurations for the Neptune III, including systems designed for diver-to-diver and diver-to-surface communication.

This can be particularly useful for:

• Dive instructors working with students
• Professional and commercial diving
• Public safety diving
• Scientific diving
• Guided diving
• Underwater media production
• Teams working in low-visibility environments

The ability to speak underwater can change communication from a collection of hand signals into an actual conversation.

It is important, however, to remember that communications are an optional system rather than a built-in guarantee of voice communication on every Neptune III configuration.

Comfort is more than simply having no mouthpiece.

The Neptune III uses a six-strap head harness designed to distribute the load around the head. Its face seal uses OCEAN REEF's patented bellows-style double-S spring-profile design, intended to create a floating effect against the face.

The quick-release buckle system is designed to make donning and doffing easier, while the included doffing handle gives the diver another way to remove the mask using one hand.

A good fit remains critical, because even the most sophisticated full face mask cannot compensate for an incorrectly sized face seal.

The Neptune III is available in two main sizes:

• Small/Medium (S/M): 10 cm to 11.5 cm chin-to-nose measurement
• Medium/Large (M/L): more than 11.5 cm

Measure from the bridge at the top of your nose to the bottom of your chin.

If your measurement falls within an area where either size may work, OCEAN REEF recommends trying the mask to determine the best fit. When correctly fitted, there should be no gap between the bottom of the chin and the silicone skirt.

Fit should always take priority over simply choosing a size based on a chart.

A full face mask creates a breathing and sealing environment around your entire face, so an appropriate seal is particularly important.

The supplied equipment depends on the exact Neptune III configuration, so it is worth checking the package before ordering.

The Neptune III package supplied for the system includes:

• Neptune III Full Face Mask with integrated second stage regulator
• Neptune III backpack
• Doffing handle
• Surface air valve
• Standard hose
• Extender kit
• Multitool

The purpose-built backpack is also more than simple storage. It includes a dedicated mask compartment and a lower compartment with draining mesh intended to accommodate items such as the first stage, hoses and octopus.

Keeping the IDM protected and organised between dives is particularly useful because the mask is a complete breathing system rather than just a piece of face protection.

A full face mask should never be treated as a novelty piece of dive equipment.

The Neptune III package is CE marked and certified as Category III Personal Protective Equipment under EU Regulation 2016/425. OCEAN REEF's documentation states that the Neptune III package conforms to EN 250:2014 and has been tested for use in water temperatures below 10°C.

The manufacturer also provides specific procedures for pre-dive checks, donning, diving, post-dive care and emergency procedures in its owner documentation.

Before diving an IDM, divers should understand the equipment-specific procedures rather than assuming that experience with a conventional regulator automatically covers everything.

Training, correct fitting, pre-dive checks and appropriate servicing are fundamental parts of using a full face diving system safely.

An IDM isn't necessarily something you buy simply because it looks futuristic.

It makes the most sense when its advantages match the way you actually dive.

A Neptune III could be particularly interesting if you:

• Want to breathe naturally through your nose underwater
• Experience jaw fatigue with conventional regulators
• Want a large field of vision
• Dive regularly in colder conditions
• Need or want underwater communications
• Work as a dive professional
• Want an integrated equipment setup
• Spend long periods underwater

On the other hand, a conventional mask and regulator may remain the simpler choice for divers who prioritise minimal equipment, travelling light or switching easily between different regulators and masks.

The right choice ultimately depends on your diving, your training and what you value most from your equipment.

The difference is easiest to understand by looking at the two systems side by side.

The important thing is that neither setup eliminates the need for proper diving skills.

An IDM changes how the equipment works, but it does not replace good buoyancy, situational awareness, buddy procedures or emergency training.

Because the Neptune III combines a mask and regulator into one system, maintenance deserves attention.

After diving, follow the manufacturer's cleaning and storage instructions, particularly after exposure to salt water. The regulator and mask should be kept clean, inspected regularly and serviced according to the manufacturer's requirements.

OCEAN REEF's current Neptune III manual includes dedicated sections covering maintenance, cleaning, disinfection, storage and troubleshooting.

Avoid treating the Neptune III like an ordinary mask that can simply be thrown into a kit bag after a dive.

Looking after the complete system properly helps protect both its performance and its longevity.

OCEAN REEF's supplied warranty information states that the Neptune III Full Face Mask carries a lifetime warranty, while other components are covered for two years.

Warranty terms can depend on the specific component and conditions of use, so always check the applicable documentation supplied with your equipment.

A full face mask is not simply a different-looking dive mask. It is a different approach to breathing, visibility and equipment integration underwater. For divers who value natural breathing, comfort, a broad field of view or underwater communication, the Neptune III Full Face Mask offers a highly integrated way to experience those benefits.

And as with any life-support equipment, the most important feature isn't how futuristic it looks — it's understanding the system, getting the fit right, using it within its certification and keeping it properly maintained.

And remember that if you need any help with the choice, you can always email us at support@mikesdivestore.com, schedule a video consultation, or drop by our Chiswick store for expert, face-to-face advice.