Decompression Sickness Myths vs Facts for Recreational San Diego Freediving

Decompression sickness (DCS) carries a reputation in the freediving community that often outpaces the actual science. If you’re freediving at Sunset Cliffs, La Jolla Cove, or the kelp forests off Point Loma, you’ll hear plenty of myths from other divers—many of them persistent, some potentially dangerous. Here’s what you actually need to know.

The Core Myth: Freediving and DCS

The biggest misconception: Recreational freediving causes decompression sickness the way scuba does.

The reality: True decompression sickness from nitrogen absorption is extremely rare in freediving. DCS develops when a diver breathes compressed air at depth, absorbs excess nitrogen, and surfaces too quickly without allowing that nitrogen to offgas safely. Freedivers don’t breathe compressed air underwater—they work on a single breath held at the surface. No compressed air, no significant nitrogen loading, no DCS.

What can happen to freedivers is shallow water blackout (SWB) or hypoxic blackout, which is entirely different and far more prevalent in San Diego’s recreational diving community. This is why training matters.

Myth: “I’ll Get the Bends if I Dive Too Deep”

Many recreational freedivers at sites like Torrey Pines or Bird Rock believe that diving beyond 40 feet automatically creates DCS risk. This isn’t how the physiology works.

During a freedive, your body doesn’t absorb excess nitrogen because there’s no compressed air forcing nitrogen into your tissues. Your single breath of surface air is already at atmospheric pressure. As you descend, pressure increases, but you’re not taking in additional nitrogen. When you surface, pressure decreases, and any minimal nitrogen absorbed during your dive offgases naturally during normal breathing.

The exception: If you use a rebreather or any equipment that delivers compressed gas at depth, DCS becomes a real concern—but that’s technical diving, not recreational freediving.

Myth: “You Can’t Dive Again After Freediving”

Some divers believe that after a freedive session, they need to wait hours before scuba diving (or vice versa). The concern is residual nitrogen.

The fact: A single recreational freedive loads virtually no excess nitrogen. If you freedive in the morning at Scripps Canyon and want to scuba dive in the afternoon, the physiological risk from nitrogen loading is negligible. However, fatigue, hydration, and overall safety protocols matter more. Make sure you’re physically recovered, well-hydrated, and following standard dive planning. The real issue isn’t nitrogen—it’s your body’s readiness for another dive.

Myth: “Fast Ascents = DCS”

This is partially true for scuba but misleading for freediving. Yes, rapid decompression can theoretically cause problems—but only if excess nitrogen is present to begin with.

During a freedive, ascending quickly is actually safer than ascending slowly, because it reduces your time under pressure and minimizes the already-minimal nitrogen uptake. The dangerous part of a fast ascent in freediving is hyperventilation-related blackout risk before descent, not DCS after.

What Freedivers Actually Need to Worry About

Shallow water blackout (SWB): This is the real threat. It happens when hypoxia (oxygen deprivation) causes unconsciousness, typically on ascent as CO₂ levels drop and your body’s urge to breathe fades. Training, buddy systems, and conservative breath-hold practices prevent this. San Diego’s popular sites—Windansea, Cabrillo Point, and the reefs near Ocean Beach—see incidents when divers push limits without proper supervision.

Nitrogen narcosis: At extreme depths (beyond recreational limits), nitrogen causes impaired judgment. Again, this requires compressed air and depths most recreational freedivers never reach.

Pulmonary barotrauma: Ascending while breath-holding and expanding air in your lungs can cause lung rupture. This is real, serious, and entirely preventable through proper training and never holding your breath while ascending.

San Diego-Specific Considerations

Local conditions matter. Cold water (50–60°F in winter) increases oxygen consumption and shortens safe breath-hold times. Kelp forests at La Jolla and Point Loma can disorient divers and extend bottom time unintentionally. Strong currents at sites like The Wreck require efficient diving and quick ascents.

None of these factors cause DCS in the traditional sense, but they do increase overall risk and fatigue. Respect the conditions, know your limits, and dive within your training.

The Bottom Line

Decompression sickness is not a significant risk for recreational freediving in San Diego. Shallow water blackout, pulmonary barotrauma, and fatigue are. Get proper training, dive conservatively, always use a buddy, and understand the actual risks—not the myths. Your safety depends on knowing the difference.

Track conditions at your favorite San Diego dive sites with the Element app to time your dives for optimal safety and visibility.