freefall
Dean's Blue Hole
The deepest blue hole on earth — a vertical cave to 202 m.
Bahamas
Freediving, engineered
know thedepth.
A freediving platform that trains your breath, maps the pressure at every depth, and keeps you safe on the way down and back.
photo · ArtHouse Studio
−130 m · CWT record
01
How it works
Three steps. No tank, no bubbles, just you and the line.
/ 01
Learn the breath
The breath-up is the whole game. Slow, deep, and then empty — the dive starts before the surface does.
/ 02
Train the tolerance
CO₂ tables build the burn, recovery builds the reserve. The urge to breathe is a signal you can move.
/ 03
Go down
Equalize early, freefall late, surface slow. And never — not once — without a buddy.
02
The five disciplines
One calm, five ways to measure it.
STA — Static apnea
Float face-down, don't move. Pure breath, no distance.
DYN — Dynamic
Horizontal distance in a pool, fins on.
CWT — Constant weight
Fin down the rope and back. The classic depth discipline.
CNF — No fins
Breaststroke to the bottom. Nothing but muscle.
FIM — Free immersion
Pull the rope, no fins. Depth in its rawest form.
Equalization
Frenzel and friends — the skill that unlocks the deep.
03
The pressure table
One atmosphere every ten meters. Watch your lungs shrink on the way down.
0m
surface−120 m
pressure at depth · scroll the table
depthpressurelung volumenote
0 m1.0 atm100%surface — one breath's worth
10 m2.0 atm50%the eardrum's first test
20 m3.0 atm33%⅓ lung volume — equalize or turn
30 m4.0 atm25%residual-volume territory
40 m5.0 atm20%the freefall begins
50 m6.0 atm17%
60 m7.0 atm14%the door to the deep
70 m8.0 atm13%
80 m9.0 atm11%2–3× the pressure of a car tire
90 m10.0 atm10%
100 m11.0 atm9%the century club
110 m12.0 atm8%
120 m13.0 atm8%beyond every CWT record
04
The blue, up close
Shot where the bottom disappears.
05
The slow descent
One line, one breath, all the way down.
the descent
06
The breath-hold board
Hold it. The clock is honest.
0:00.0
your best — none yet
Press and hold. Release to stop. Your time stays in this browser — never sent anywhere.
STA — Static ApneaStéphane Mifsud11:352009
STA — Static Apnea (O₂)Budimir Šobat24:372021
CWT — Constant WeightAlexey Molchanov133 m2023
CNF — No FinsWilliam Trubridge102 m2016
FIM — Free ImmersionAlexey Molchanov133 m2023
DYN — DynamicMateusz Malina316.53 m2022
world records · AIDA / CMAS, verified
07
Four waters
Every depth has its own character.
mediterranean
Kalamata
The Mediterranean's clearest training water.
Greece
blue
The pelagic zone
Open water where the bottom disappears.
offshore
shallow
The reef line
Warm, bright, and forgiving — where you learn.
reef
From the desk of Soren Aalto
Every freediver remembers the first ten meters.
I was nineteen the first time I pulled myself down a line and felt my lungs shrink to a third and my heart slow to thirty beats a minute. Nothing else in my life has ever been that quiet.
Most people think freediving is about how long you can hold your breath. It isn't. It's about how calmly you can come back up. The dive is the easy part — the surface is where the work happens.
FATHOM is the thing I wish I'd had that first season: a pressure table I could feel, a training plan I could trust, and one rule above all — never dive alone.
Soren AaltoFounder, FATHOM
08
By the numbers
Live, from our backend.
412k
meters descended
1.2M
breath-holds logged
48k
divers training
100%
dives with a buddy
09
Loved by divers
People who finally went quiet.
★★★★★
"The CO₂ tables changed my static from 2:30 to 4:10 in six weeks. The burn finally has a shape."
Lena M.Pool freediver
★★★★★
"I finally understand equalization. The pressure table made it click in one afternoon."
Tomás R.AIDA 2
★★★★★
"'Never dive alone' isn't a slogan here — it's on every page. It saved me once."
Amara S.CWT 40 m
10
The roadmap
Where we're going.
Q4 2026
Breath-hold training engine + pressure tables, live in beta.
Q1 2027
A depth log with buddy check-ins and live session tracking.
Q2 2027
Community depth boards and verified personal records.
Q3 2027
Instructor certification track and a pool-partner finder.
11
Questions, answered.
Is freediving dangerous?+
Only alone. Blackout is real, and it's survivable — if someone is watching. Every rule we teach exists to keep you in arm's reach of a buddy.
Do I need to be athletic?+
No. You need to be calm. A relaxed beginner out-dives a tense athlete every time, because relaxation is what saves oxygen.
What gear do I need to start?+
A low-volume mask, long-blade fins, a wetsuit, and a buddy. Everything else is optional. We'll walk you through the rest.
Is this just an app?+
No — it's training plans, depth data, and a community. The app is just how it reaches you between dives.
Do you track my dives?+
Only what you log yourself, and only to build your training plan. Your depth log is yours; export it any time.
Is there a membership fee?+
No. The core training engine stays free through beta and after launch.
The deep is waiting.
know the depth.