Why Equalization Gets Harder as You Go Deeper — And How to Fix It

https://www.youtube.com/watch?v=ObfoWF5VNwE

Do you feel like equalization becomes more difficult the deeper you dive?

You might notice it starting as shallow as 5 meters, or it may only show up past 30 meters. Either way, the experience is the same: what felt smooth and easy near the surface suddenly requires more effort. Eventually, it can feel like you’ve hit a wall.

This article explains why that happens — and what you can do about it.

The End-Range Problem

To understand what’s happening, it helps to compare equalization to other types of movement.

Example 1: Bending Your Arm

Lift your arm and bend your elbow. As your hand gets closer to your shoulder, it becomes harder to continue. The closer you get to your end range of motion, the more effort is required. Eventually, you simply cannot move any further.

The effort increases as you approach your mechanical limit.

Example 2: Fully Exhaling

Try exhaling all the air out of your lungs. As you approach the end of your exhale, it takes more and more effort to push out the remaining air. Eventually, no matter how hard you contract, no more air leaves your body.

You’ve reached your residual volume — the end range of expiration.

Equalization Works the Same Way

When you equalize using Frenzel or mouthfill, you are compressing air above the glottis and sending pressure to the ears.

That system also has an end range.

As you go deeper:

• Pressure increases

• Air spaces compress (Boyle’s Law)

• The available air volume shrinks

• You need more effort to generate equalization pressure

Eventually, you reach what I like to describe as the “throats residual volume” — the point where the air above the glottis is so compressed that you cannot generate additional pressure.

At that point, unless you bring more air up from the lungs, equalization stops.

Boyle’s Law and Air Compression

Boyle's Law states:

If temperature remains constant, the volume of a gas is inversely proportional to the absolute pressure.

In simple terms: As you go deeper, air compresses.

The deeper you dive, the smaller your equalization air volume becomes. As it shrinks, you approach your functional end range (throats residual volume).

Why Some Divers Go Deeper Than Others

Every equalization method eventually reaches the throats residual volume. The difference between divers is how much air they start with, how often they bring more and how efficiently they manage it.

For example:

• A basic Frenzel with good air shift might limit you around 40–50m.

• A well-executed mouthfill might carry you to 60m.

• A refined mouthfill could take you to 80m, 100m, 130m, and beyond.

Mouthfill is not magic. It simply gives you a larger volume of air. The more air you begin with, the longer it takes to compress down to your throats residual volume.

Skill and tactics determine how deep that threshold is reached.

The Two Ways to Bring Air Above the Glottis

To avoid hitting the throats residual volume too early, you must bring air from the lungs to above the glottis. There are two primary methods:

1. Reverse Packing

Well know word, but usually misunderstood, reverse packing sucks air upward before compression limits you.

2. Abdominal Contraction (essentially a Valsalva)

• N-charge (for Frenzel)

• M-charge (for mouthfill)

All of these are simply air-shifting strategies.

They serve one purpose : Increase the air volume for equalization.

Frenzel vs. Mouthfill — Which Should You Use?

If you’re using Frenzel only and struggling before 40–50m, there are likely technical refinements you can make.

If you’re on a short training window — say a one or two-week trip — switching to mouthfill may give you immediate comfort and additional depth. It can reduce stress and increase motivation.

However:

• Improving Frenzel requires skill development.

• Learning mouthfill also requires skill development.

• Neither is a shortcut.

Often, the limitations you experience with Frenzel will reappear later during mouthfill. They are not bypassed — only delayed.

The key is choosing the path that keeps you progressing with the least resistance.

If You’re Stuck

If you’re unsure what is limiting you — air shift, tongue control, glottis management, timing, or something else — a structured consultation can help.

Testing, feedback, and targeted drills can clarify exactly what needs work and prepare you properly for the coming season.

Equalization difficulty at depth is not random. It is mechanical. And once you understand the mechanism, you can train it. Send me an email to book your consultation.

Dive safe.