Solving Ear Problems for Diving: How I Converted My Hollis M1 to the IST ProEar System

For the better part of 15 years, the most consistent feature of my diving life has not been a logbook full of beautiful sites or a hard drive full of underwater photographs. Instead, it has been my inability to go on a tropical dive trip without a large supply of Amoxicillin and Otopain antibiotic ear drops.

I have dealt with recurring ear infections for my entire diving career, losing many dives to swollen ears and the massive pain that comes as pressure builds against tightening ear walls. Liveaboard trips reliably ended with a week of antibiotics. Multi-week trips always had to be broken up by a course of medication, and I’ve even lost 50% of the hearing in one ear due to scar tissue on the eardrum from all the infections.

Over the years, I have tried almost everything to fix it: swimmer's ear protection, ear-drying routines, fresh-water rinses, alcohol drops to evaporate stagnant water, Doc's Proplugs, surfer's ear plugs, hoods, and more. Yet, on last month's trip to Lembeh, I still ended up with three ear infections over 21 days of diving—even after using a hood, earplugs, swimmer's ear drops, and cleaning daily.

The Solution? A PRO IST ear mask?

There was one solution I was aware of, though: the IST Pro Ear mask, affectionately known in the dive industry as the “Mickey Mouse mask” or the “Princess Leia” mask. Years ago, I had spoken to awesome photographer and friend of Inside Scuba, Nick More, who famously uses this setup. He told me that without it, he might well have had to quit diving altogether; it has literally saved his main hobby and passion.

How the IST System Actually Works

The IST ProEar mask, in its factory form, is essentially a standard silicone-skirted dive mask with two dome-shaped silicone cups attached on either side. These cups seal against the side of your head, covering each external ear. A flexible silicone tube, about the diameter of a pencil, runs between each cup and the main mask body.

The clever part is what those tubes actually do. The ear cups are not sealed air pockets, which would compress on descent and squeeze your eardrums from the outside—the exact trap that ordinary earplugs fall into. Instead, the tubes connect the cup interiors directly to the airspace inside your mask. When you exhale a small puff through your nose to equalize the mask on descent, you simultaneously pressurize the ear cups to the exact same pressure. Your outer ear is now sitting in dry air at ambient mask pressure, rather than in wet, cold water at ambient sea pressure.

Three major benefits follow. First, your outer ear stays bone dry from the moment the mask seals, which puts an end to ear canal infections. Second, the gradient your middle ear has to fight is now air-to-air through a slack eardrum rather than water-to-air through a stretched one, making equalization dramatically easier. Finally, the eardrum is no longer mechanically pushed inward by a column of seawater, which removes the primary cause of low-grade barotrauma.

There is one major drawback to this solution, though: the mask they have fitted the system to is quite possibly the ugliest mask ever created. In addition to looking terrible and old-fashioned, it just isn’t a very good mask. It has a poor fit and features dual lenses, which is a big "no-no" for me.

Converting the IST Pro Ear system to Fit Your Own Mask 

I have been diving with the same mask for over 10 years: the Hollis M1. I adore it. As an underwater photographer, the mask you use is incredibly important; the M1 offers a fantastic field of view, and its black skirt blocks out distracting ambient light when you are looking through the viewfinder.

The single lens gives you a wide, almost wraparound field of view, while the frameless construction makes it low-volume, which means easier clearing. The skirt is made of a thick, supple black silicone that seals beautifully across a wide range of face shapes. Converting the M1 meant keeping all of those incredible features and just bolting on the ear system.

Fortunately, the M1 is an excellent candidate for conversion. The skirt is thick enough in the temple region to take a port fitting without distorting. There is also plenty of clearance between the skirt edge and the frame seal, so cutting a hole does not compromise the main waterproof seal. Because of the single-lens construction, the inner surface of the skirt is uncluttered, making it easy to secure the system from inside the mask.

If you are considering this same conversion on an M1, the short answer is: it works, and it works incredibly well. If you are careful, you will end up with a custom mask that actually performs better than the factory ProEar, simply because the underlying mask is vastly superior.

The Conversion, Step by Step

When you first buy an IST ProEar mask, the system looks as though it is permanently glued and sealed into the frame. On closer inspection, however, I realized that isn't the case at all. Instead, the threaded tubes are simply held in place by two hex nuts on the inside of the mask. Once you unscrew these two nuts, the entire ear system easily pops right off.

The secret to how it seals is that the hole in the skirt is significantly smaller than the main tubes and the hex nut. Because the threaded end of the tube is narrower, you only need to make a hole large enough for that threaded portion to pass through. The silicone mask skirt is then clamped firmly between the flange of the tube and the internal hex nut. There is absolutely no glue or silicone sealant involved here; it is purely the tightness of the nut compressing the silicone that creates the waterproof seal.

First, I stripped off the Hollis mask strap and removed the system from the IST mask by simply undoing both internal hex nuts, allowing the tubes to pop right out. I then consulted a few members of my engineering team from work about the best way to pierce the Hollis mask. We initially tried using a heated metal rod to melt clean holes into the silicone skirt. However, after a little trial and error, we found that a leatherworker's hole punch was the absolute best solution. It allowed us to punch incredibly precise holes of the perfect diameter.

Next came the reassembly: threading the tubes through the new holes and securing them with the internal hex nuts. Because the silicone skirt on my Hollis mask is slightly thicker than the one on the IST mask, the hex nuts don’t thread down quite as far. If loosening becomes an issue over time, I will likely add a drop of glue to the threads in the future, but for now, it feels secure.

Once the tubes are sealed in place, you can feed the Hollis mask strap back through the ear cups. This is a massive upgrade in itself, as the Hollis strap is significantly more comfortable and robust than the stock IST one.

The final step was a quick test in the swimming pool to ensure everything was watertight. This custom rig will now become my go-to mask setup for all warm-water diving. It means when I dive at home, I can still use a standard Hollis M1 mask, and keep this specialized one strictly for vacations. It isn’t practical to wear this setup in extreme cold water due to drysuit hood constraints, but fortunately, I never seem to get ear infections on those polar trips anyway.

I will report back on how this modification fares over time. Ear issues are easily the worst part of diving for me; infections have ruined so many trips and, honestly, were starting to make me dread the thing I love most—underwater photography in warm, tropical seas. Hopefully, this custom mask is the permanent solution.

It still might not be the most fashionable gear choice on the boat, and you might feel a little ridiculous wearing it. But as my good friend Nick More rightly pointed out: you’ll feel far more ridiculous sitting on the dive deck watching everyone else splash into the water while you nurse yet another ear infection.