The news over the past few days has been dominated by this story.
https://divemagazine.com/scuba-diving-news/five-italian-divers-die-in-maldives-cave
What went wrong?
Javier Cantellops owner of Maui Diving explains it bluntly.
The bottom line. There are two types of divers who are dangerous, the under trained and the over confident.
This disaster should not dissuade you from SCUBA diving. What happened to these divers was a preventable tragedy. Violating PADI depth limits was the first mistake. PADI depth limits depend on the diver’s certification level, training, age, and conditions. These are the standard recreational limits taught by Professional Association of Diving Instructors:
Certification / Diver TypeRecommended Maximum DepthDiscover Scuba Diving40 ft / 12 mOpen Water Diver60 ft / 18 mJunior Open Water (ages 10–11)40 ft / 12 mJunior Open Water (ages 12–14)70 ft / 21 mAdventure Diver (Deep Adventure Dive completed)100 ft / 30 mAdvanced Open Water Diver100 ft / 30 mDeep Diver Specialty130 ft / 40 mRecreational no-decompression limit130 ft / 40 m
Important concepts:
Recreational PADI diving is generally limited to 130 ft / 40 m maximum.
Air consumption rises rapidly with depth:
At 66 ft / 20 m you consume air about 3× faster than at the surface.
At 99 ft / 30 m about 4× faster.
At 130 ft / 40 m about 5× faster.
Narcosis risk becomes noticeable for many divers around 80–100 ft (24–30 m).
PADI recreational training emphasizes:
staying within no-decompression limits,
slow ascents (typically ≤30 ft/min or 9 m/min),
a safety stop at 15 ft / 5 m for ~3 minutes on most dives.
A few additional PADI-related rules:
Junior divers must dive with an adult professional or certified parent/guardian.
Technical diving beyond 130 ft requires separate training (TecRec, trimix, decompression procedures, redundant gas, etc.).
Cave diving, overhead environments, and decompression diving are outside standard recreational Open Water training.
For perspective:
60 ft = about 18 m
100 ft = about 30 m
130 ft = about 40 m
Why PADI chose those depth limits
Professional Association of Diving Instructors depth limits are primarily based on four risk factors:
Nitrogen narcosis
Gas consumption
No-decompression limits
Emergency ascent feasibility
The deeper you go, the faster all four become problematic.
Nitrogen narcosis (“rapture of the deep”)
Breathing compressed air at depth increases the partial pressure of nitrogen. Nitrogen begins affecting the brain similarly to alcohol or anesthetic gases.
Typical effects:
slowed thinking
poor judgment
overconfidence
tunnel vision
fixation
delayed reaction time
Many divers first notice mild narcosis around:
DepthTypical Effects60–80 ft (18–24 m)Mild slowing, subtle impairment100 ft (30 m)Noticeable impairment in many divers130 ft (40 m)Significant impairment possible
This is one major reason:
Open Water is limited to 60 ft / 18 m
Advanced is limited to 100 ft / 30 m
Recreational max is 130 ft / 40 m
Even experienced divers are affected — they may simply recognize it better.
Gas consumption rises dramatically
Pressure underwater increases by approximately 1 atmosphere every 33 ft / 10 m.
P=P0+d33P = P_0 + \frac{d}{33}P=P0+33d
Where:
PPP = total pressure in atmospheres
P0P_0P0 = surface pressure (1 ATA)
ddd = depth in feet
That means:
DepthPressureAir UseSurface1 ATAnormal33 ft / 10 m2 ATA2×66 ft / 20 m3 ATA3×99 ft / 30 m4 ATA4×132 ft / 40 m5 ATA5×
So a diver who breathes:
0.5 cu ft/min at surface
would consume:2.5 cu ft/min at 130 ft.
A tank disappears surprisingly fast at deep depths.
No-decompression limits become very short
The deeper you go, the faster nitrogen accumulates in tissues.
Approximate recreational no-decompression limits:
DepthApproximate NDL60 ft / 18 m~55 min80 ft / 24 m~30 min100 ft / 30 m~20 min130 ft / 40 m~10 min
At 130 ft:
you can become deco-obligated very quickly,
and a problem can escalate rapidly.
Why ascent emergencies become harder deep
At shallow depths:
a direct ascent may still be survivable.
At 130 ft:
gas-sharing ascents are long,
panic risk rises,
buoyancy errors magnify,
omitted decompression becomes dangerous.
A runaway ascent from depth can cause:
arterial gas embolism,
pneumothorax,
severe decompression sickness.
Why technical divers go deeper
Technical diving uses:
staged decompression,
redundant gas,
helium mixes (trimix),
decompression algorithms,
extensive emergency drills.
Helium reduces narcosis because it is less narcotic than nitrogen.
Technical divers commonly exceed:
130 ft recreational limits,
but with entirely different procedures and equipment.
Examples:
Tec 40: decompression begins
Trimix divers: 200–300+ ft possible
Cave divers: overhead + decompression complexity
This is a completely different risk category from recreational diving.
Real-world experienced diver practices
Many experienced recreational divers:
stay shallower than their certification permits.
Why?
Because:
marine life is often better above 80 ft,
colors/light are better,
dives last longer,
safety margins are larger,
fatigue is lower.
In places like Belize or Catalina Island, many excellent dives are:
30–70 ft.
Deep dives are often:
shorter,
darker,
colder,
more task-loaded.
Comparison with other agencies
National Association of Underwater Instructors
Historically somewhat more “autonomy oriented.”
Open Water often trained somewhat deeper in older eras.
More emphasis on dive planning independence.
Scuba Schools International
Very similar recreational limits to PADI today.
Global Underwater Explorers
More conservative philosophy:
strong buoyancy standards,
team procedures,
standardized gas planning.
A useful practical rule
A lot of seasoned divers informally think:
Depth Zone
General Risk Increase
0–60 ft relatively forgiving
60–100 ft moderate risk escalation
100–130 ft serious recreational diving
>130 fttechnical diving territory
