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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.

Boat diving

Method · Last reviewed 2026-08-10

Spearfishing from a vessel, which removes the swim and adds the two things most likely to kill a diver: propellers and drift.

Safety

Boat traffic and being seen — Can cause serious injury or death

A diver at or near the surface is close to invisible from a boat, and a vessel under way cannot stop or turn in the distance available once one is seen. Propeller injuries are catastrophic and frequently fatal. The boat involved is often the divers' own.

What reduces it: A conspicuous flagged float per diver, kept close rather than trailing. Somebody competent aboard, watching, with the engine in neutral whenever anybody is near the water. Approach divers up-current and stop clear. Surface with an arm raised and look up before breaking the surface. Choose ground away from navigation channels and moorings.

Worse when:

  • Chop or glare, which hide a float as effectively as a head
  • Busy inshore water in summer
  • Live-boating, where the vessel is moving while divers are down

Drowning and immersion — Can cause serious injury or death

A diver who surfaces to find the boat has drifted, or has moved to another diver, is alone in open water with no platform. In any sea state, separation escalates quickly from inconvenient to serious.

What reduces it: Agree the drift plan and the recall signal before the first entry. Keep divers together and the boat up-drift. Every diver carries a float they can rest on and a means of signalling. Nobody enters until somebody aboard has acknowledged them.

Shallow water blackout and breath-hold loss of consciousness — Can cause serious injury or death

The mechanism is the same as everywhere else in this section, but boat diving introduces a specific failure: a buddy pair that becomes a group of divers loosely around a boat, where everybody assumes somebody else is watching and nobody is.

What reduces it: One up, one down as a NAMED pairing, not as a general intention. Assign pairs explicitly at the start of the day and dive them.

Precautions that always apply here

  • Never spearfish or freedive alone.
  • Dive one up, one down: one diver down, one on the surface actively watching, every single dive.
  • Never hyperventilate before a breath-hold. It delays the urge to breathe without adding oxygen, which is precisely the mechanism behind shallow water blackout.
  • Tell somebody where you are going and when you expect to be back.
  • Carry a charged phone in a waterproof case, or another means of calling for help.

A boat transforms spearfishing. It reaches ground no swimmer can, it carries kit, it gives somewhere to warm up, and it means a diver who is in trouble can be recovered rather than swum to.

It also introduces the two hazards that dominate spearfishing fatality reports after blackout: boat traffic, and separation. A diver in the water is close to invisible; a boat that cannot see them cannot avoid them, including the boat they came on. And a diver who surfaces to find their vessel has drifted, or has gone to pick up somebody else, is a person alone in open water.

Everything in the discipline's boat practice — the flag, the flotation, the diver-recall signal, the rule about who stays aboard, the engine going into neutral before anybody is near the water — exists because of those two facts.

What it is

Spearfishing conducted from a vessel, whether anchored, drifting or live-boating with a person aboard following the divers. Covers everything from a small inflatable on inshore reef to an offshore boat over open water.

How it works

Divers enter from the vessel, work the ground on breath-hold dives with the float marking their position, and are recovered by the vessel. The boat either anchors, drifts with the divers, or is actively handled by somebody who remains aboard. Which of those three applies is the single biggest safety decision of the day, and it is made before anybody gets wet.

What it is for

To reach ground that cannot be swum to, to cover more of it, and to have a platform for rest, warmth and — critically — recovery of a diver in difficulty.

Setting it up

  • Somebody competent stays aboard and is watching the water. This is not a passenger; it is a role.
  • Fly the recognised dive flag, and know that what it obliges other vessels to do varies by country.
  • Engine in neutral before anybody is in the water near the boat, without exception.
  • Agree the recall signal, the drift plan and what happens if a diver surfaces away from the boat, before the first entry.
  • Every diver carries their own float and line, so the boat is tracking marked positions rather than heads.

Advantages

  • Access to ground no shore diver can reach.
  • A platform for warmth, rest, food and safe kit handling.
  • A diver in difficulty can be recovered quickly rather than swum to.
  • Conditions can be moved away from rather than endured.

Limitations

  • Introduces propeller risk, which is catastrophic when it occurs.
  • Drift separates divers from the vessel faster than most people expect.
  • Requires somebody competent to remain aboard, which costs a diver.
  • Cost, logistics and dependence on a launch and a forecast window.

Conditions

Boat diving tolerates more swell than shore diving because there is no entry over rock, but it is limited by what is safe and workable at the surface: chop makes divers hard to see, wind against tide makes station-keeping difficult, and a rising sea turns recovery into the difficult part of the day. Visibility matters more here because the ground is chosen rather than walked to, and a wasted trip is expensive.

Common mistakes

  • Everybody diving and nobody watching the boat or the water.
  • Underestimating drift, so divers surface a long way from where they expect the boat to be.
  • Manoeuvring near divers with the engine engaged.
  • Assuming a dive flag obliges other vessels to do something specific — that varies by jurisdiction and many skippers do not know it.
  • Long float lines trailing behind divers, which are both an entanglement hazard and a propeller hazard.

Where to go next

What it catches

What these connections rest on (2)

Practitioner consensus — 2 connections

Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.

  • Blue cod

    A practitioner claim about how Parapercis colias is commonly fished, following from where and how it feeds.

    • General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated practitioner accounts of fishing for blue cod.Citation checked — the work exists and is described correctly
    • Sea Angler — Bauer Media (Specialist angling publication)Relied on for: Practitioner treatment of the methods used for blue cod and comparable species.Citation checked — the work exists and is described correctly

  • Lingcod

    A practitioner claim about how Ophiodon elongatus is commonly fished, following from where and how it feeds.

    • General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated practitioner accounts of fishing for lingcod.Citation checked — the work exists and is described correctly
    • Sea Angler — Bauer Media (Specialist angling publication)Relied on for: Practitioner treatment of the methods used for lingcod and comparable species.Citation checked — the work exists and is described correctly

Related techniques

What these connections rest on (1)

Authoritative guidance — 1 connection

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

  • Spearfishing

    A safety characterisation held to an authoritative standard, because getting it wrong changes what precautions a reader takes.

    • BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: The visibility problem a diver presents to vessels and the practice that addresses it.States this directlyCitation checked — the work exists and is described correctly
    • RNLI water safety guidance: cold water shock and Float to Live — Royal National Lifeboat Institution (Water-safety or diver-training authority)Relied on for: Immersion and separation risk for a person in open water without a platform.FishingHQ's interpretation of what it saysPassage read and verified

Skills behind it

What these connections rest on (6)

Authoritative guidance — 5 connections

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

  • How a band speargun works

    Where loaded-gun handling errors occur.

    • FAO fishing gear types and fishing technology information — Food and Agriculture Organization of the United Nations (Scientific institute)Relied on for: Gear classification and construction for spears and powered spear devices.States this directlyCitation checked — the work exists and is described correctly

  • Loss of motor control, and what it is warning of

    Where the misreading most often happens.

    • DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Hypoxic symptoms in breath-hold diving and their relationship to blackout.States this directlyPassage read and verified

  • Seasickness and boat days

    The setting where it occurs.

    • BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Diving safety guidance on fitness to dive, including illness, medication and boat operations.States this directlyCitation checked — the work exists and is described correctly

  • When to call a dive off

    The setting where sunk cost most distorts the judgement.

    • RNLI water safety guidance: cold water shock and Float to Live — Royal National Lifeboat Institution (Water-safety or diver-training authority)Relied on for: Water safety guidance on assessing conditions and on decision-making before entering the water.States this directlyPassage read and verified

  • Why spearfishing is never a solo activity

    The commonest false substitute for buddying.

    • AIDA International freediving education and safety standards — AIDA International (Water-safety or diver-training authority)Relied on for: Freediving education standards establishing the one-up-one-down buddy structure and surface observation through ascent and recovery.States this directlyCitation checked — the work exists and is described correctly

Practitioner consensus — 1 connection

Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.

  • Shore diving and boat diving compared

    A mechanism edge from a record to the reasoning beneath it, resting on practice reported consistently across independent sources rather than on experiment.

    • BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Recreational diving safety practice including buddy procedure, entry and exit, surface marking and the decision to abort.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: Freediving safety guidance including the buddy system, one-up one-down procedure and blackout risk.States this directlyPassage read and verified

Compared with

What these connections rest on (1)

Authoritative guidance — 1 connection

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

  • Shore diving

    Both formats and their characteristic hazards are described in the diving and freediving safety guidance cited, and the comparison asserts nothing beyond what those sources set out.

    • BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Recreational diving safety practice including buddy procedure, entry and exit, surface marking and the decision to abort.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: Freediving safety guidance including the buddy system, one-up one-down procedure and blackout risk.States this directlyPassage read and verified

Safety 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.

  • Buoyancy aids for anglers

    Diver safety guidance underlying this connection.

    • BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Diving guidance on surface flotation and buoyancy for divers working from vessels.States this directlyCitation checked — the work exists and is described correctly

  • Surface markers and boat traffic

    Diving from and around boats puts divers in transit routes.

    • 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. Diving from and around boats puts divers in transit routes.States this directlyPassage read and verified

Check the rules before you fish

Fishing laws, bylaws, access rules, seasons, bait restrictions and permitted methods vary by location and can change. Check the current rules from the relevant authority and the water you intend to fish before fishing.

Check with:

  • Current national or regional law for where you are fishing
  • Current local bylaws
  • The relevant fisheries authority
  • The landowner, club or fishery whose water it is
  • Any restrictions specific to the species or the method you intend to use

Sources for this page

  • BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Buddy protocol, surface marking and the visibility problem divers present to vessels.States this directlyCitation checked — the work exists and is described correctly
  • RNLI water safety guidance: cold water shock and Float to Live — Royal National Lifeboat Institution (Water-safety or diver-training authority)Relied on for: Cold water and immersion risk applying to a diver separated from a vessel.FishingHQ's interpretation of what it saysPassage read and verified

How FishingHQ labels evidence is explained in the evidence policy.

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