A freediver hanging motionless at depth beneath the platform, suspended in blue

Freediver · Coach · Athlete · Dominica

Fall calm,
rise strong.

The UK's deepest no-fins freediver. 8th in the world. AIDA Master Instructor, based in Dominica.

Photograph · Allie Reilly
I · The surface

On one breath

Nothing had ever
felt as natural.

Long before the deep, there was the river — a Winchester College First VIII oarsman at fifteen, a GB Rowing trialist. And before the ocean, the deep he loved was overhead: an astrophysics graduate whose first vast, silent place was the night sky.

Then, locked down in Hawai'i during Covid, Harry took a breath and went underwater. That hobby became a calling: in 2022 he left the UK for Dominica — a volcanic island ringed by deep, clear water — and committed completely.

The line in his crest falls from his own star sign through the surface and into the sea — the two deeps joined by a single thread.

Harry McCahill floating on his back at the surface, breathing up before a dive The breath-up — where every dive is won Allie Reilly
II · The descent
Harry McCahill descending head-first beside the competition line with no fins CNF · no fins, no propulsion — only the body Allie Reilly

The competitor

8th in the world,
in the purest discipline.

Competing only since 2024, Harry is the deepest no-fins diver in Britain, second-deepest in British history, and holder of three national records — in Constant Weight No Fins, where a diver descends and returns on a single breath using nothing but their own body.

In 2026 he earned a wild card to the AIDA Depth World Championships in Limassol, Cyprus.

91m
CWT · Constant Weight
90m
FIM · Free Immersion
85m
CWTB · Bi-fins
80m
CNF · No Fins

8th in the world · CNF 2025 — 3 national records — World Championships wild card 2026

A no-fins freediver gliding weightless, arms spread, in a column of light from the surface

III · The deepest point

Surrender the descent;
earn the ascent.

You let go to sink — then find the will to come back

Photograph · Allie Reilly
IV · The ascent

The mindset

The hardest metres
are the last.

The ascent is where a dive is decided. The urge to breathe arrives, the body begs to rush — and the discipline is to stay slow, stay soft, and trust the work already done.

You don't fight the pressure. You meet it — one relaxed pull at a time — and let the surface come to you.

A freediver ascending the line toward the bright surface, relaxed and weightless The way up — calm under rising pressure
V · The coach
Harry McCahill in a wetsuit on the shore of Soufrière Bay, Dominica Soufrière Bay · Dominica Allie Reilly

The coach

Calm is taught,
not forced.

As an AIDA Master Instructor, Harry has certified over 100 students — from first breath-holds to competition depth. The approach is the same calm that defines his own diving: relaxation, efficient technique, and nervous-system regulation. Not pushing.

  • AIDA courses, beginner to instructor — year-round in Dominica
  • Depth coaching & competition preparation
  • One of the world's premier depth-training locations: deep, warm, still water

VI · The surface again

Rise strong.

Train with Harry in Dominica, partner with a rising GB athlete, or just follow the story — one breath at a time.

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