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Before you spearfish — this comes first

  • Get proper instruction before you spearfish. A recognised freediving or spearfishing course teaches the things that actually kill people in this sport, and reading about them is not the same as being taught them.
  • Dive with a buddy, and dive one up, one down — one diver in the water, one on the surface watching them, every dive. A breath-hold blackout is silent and gives no warning; a watching buddy is the difference between an incident and a fatality.
  • Stay inside your own training and experience. Depth and breath-hold times are personal, they change day to day, and nobody else's numbers apply to you.
  • Understand the conditions before you enter the water: visibility, current, swell, tide, boat traffic and your exit. Conditions decide whether a dive is reasonable far more often than skill does.
  • Use equipment you have been shown how to use, check it before every session, and be visible — a marked float and line are how boat traffic knows you are there.
  • Never extend a dive for a fish. No catch is worth pushing a breath-hold, and the urge to take one more second is exactly what a blackout feels like from the inside — which is to say, like nothing at all.

Equalisation and pressure

Explainer · Last reviewed 2026-08-10

Descending compresses the air spaces in the ears and sinuses, and equalisation restores the pressure balance — a technique that must never be forced through pain.

Safety

Barotrauma and pressure injury — Can cause injury needing treatment

Descending while unable to equalise pulls the eardrum and sinus linings against a rising pressure difference, causing pain and potentially rupture or middle-ear injury.

What reduces it: Equalise early and often. Stop descending the moment equalisation fails and ascend slightly. Never force a descent through ear pain, and do not dive while congested.

Pressure rises fast in the first few metres of water, faster in proportional terms than anywhere deeper. The air spaces in the middle ear and sinuses are compressed by that change, and unless air is admitted to them the pressure difference pulls on the eardrum and the sinus linings.

Equalisation is the act of admitting that air, via the Eustachian tubes. Divers use several techniques to do it, and which one suits an individual varies. What does not vary is the principle: equalise early, equalise often, and stop descending the moment it stops working.

The injury this prevents is real. Forcing a descent against a failure to equalise can damage the eardrum and the middle ear, and forcing air aggressively can cause injury of its own. Pain is the signal to stop and ascend slightly, not an obstacle to push through.

Discomfort, pressure and injury are different things

A mild sense of fullness that clears when you equalise is normal. Pain is not. Pain means the pressure difference has already become significant, and continuing to descend increases it rapidly.

The correct response to a failure to equalise is to stop descending and ascend slightly, which reduces the pressure difference and often allows equalisation to succeed. The incorrect response — continuing down while trying harder — is how eardrums are perforated.

Congestion from a cold, allergy or infection makes equalisation unreliable, and diving with it is a recognised route to ear injury. The standing advice among diving organisations is not to dive when congested.

Decongestants are sometimes used to work around this. That practice carries its own risks, including the medication wearing off at depth, and it is a matter for medical advice rather than for a fishing catalogue.

Authoritative guidance

Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.

  • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Guidance on equalisation, the significance of pain as a stop signal, and diving with congestion.States this directlyPassage read and verified
  • BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Diving governance guidance on ear and sinus barotrauma and equalisation failure.States this directlyCitation checked — the work exists and is described correctly

Why this is a training subject

The techniques divers use to equalise differ in mechanism and in how well they work at depth and in a head-down position, and learning them is a taught skill with supervised practice rather than a description to read.

FishingHQ describes what equalisation is for and what the warning signs are. It does not teach a technique, because doing so badly produces exactly the forced-equalisation injuries the page exists to prevent, and because the appropriate progression depends on the individual.

Where ear pain persists after diving, where hearing changes, or where there is any discharge or vertigo, that is a matter for medical assessment. This page does not diagnose and should not be used to decide against seeking it.

Authoritative guidance

Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.

  • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Guidance that equalisation technique is taught under supervision and that persistent symptoms warrant medical assessment.States this directlyPassage read and verified
  • AIDA International freediving education and safety standards — AIDA International (Water-safety or diver-training authority)Relied on for: Freediving education standards covering equalisation as a supervised training subject.States this directlyCitation checked — the work exists and is described correctly

Where to go next

Where it matters

What these connections rest on (2)

Authoritative guidance — 2 connections

Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.

  • Freediving for spearfishing

    A membership assertion rather than a topical one: this record teaches the discipline or its equipment, so the discipline's mandatory safety posture applies to it.

    • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Freediving and breath-hold spearfishing safety practice, including the supervision requirement that applies across the discipline rather than to particular equipment.States this directlyPassage read and verified
    • CMAS technical and sporting standards for underwater activities — Confédération Mondiale des Activités Subaquatiques (Standards body)Relied on for: Breath-hold diving safety practice and discipline definition set out by the international underwater federation.States this directlyCitation checked — the work exists and is described correctly

    Equalisation is a taught skill with real injury consequences.

    • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diver safety guidance underlying this connection. Equalisation is a taught skill with real injury consequences.States this directlyPassage read and verified

  • Spearfishing

    Descent is impossible without it and dangerous when forced.

    • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diver safety guidance underlying this connection. Descent is impossible without it and dangerous when forced.States this directlyPassage read and verified

Related reading

What these connections rest on (2)

Authoritative guidance — 2 connections

Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.

  • Depth as an environmental variable

    Equalisation exists because pressure compresses the air spaces of the head.

    • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diver safety guidance underlying this connection. Equalisation exists because pressure compresses the air spaces of the head.States this directlyPassage read and verified

  • Fitness to dive: health, medication and when not to

    The specific mechanism behind the most frequent fitness-to-dive question.

    • UK Diving Medical Committee guidance on medical standards for divers — UK Diving Medical Committee (Water-safety or diver-training authority)Relied on for: That fitness to dive is an individual clinical assessment, and the categories of condition that require one.States this directlyCitation checked — the work exists and is described correctly
    • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diving medicine guidance on health considerations for breath-hold divers.States this directlyPassage read and verified

How this compares

What these connections rest on (3)

Authoritative guidance — 3 connections

Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.

  • Equalisation, and the injuries that follow forcing it

    The technique page and the injury page answer different halves of one question.

    • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diving medicine guidance on ear and sinus barotrauma and on ceasing descent when equalisation fails.States this directlyPassage read and verified

  • Low-volume masks, and why volume matters

    The mask participates in the pressure system.

    • AIDA International freediving education and safety standards — AIDA International (Water-safety or diver-training authority)Relied on for: Freediving equipment standards including mask volume and equalisation.States this directlyCitation checked — the work exists and is described correctly

  • Mask fogging, leaking and squeeze

    The one of the three that signals a technique problem.

    • AIDA International freediving education and safety standards — AIDA International (Water-safety or diver-training authority)Relied on for: Freediving equipment practice including mask fit, volume and equalisation.States this directlyCitation checked — the work exists and is described correctly

Sources for this page

  • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Guidance on equalisation, barotrauma of the ear and diving with congestion.States this directlyPassage read and verified

How FishingHQ labels evidence is explained in the evidence policy.

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