Separating Myth from Reality for Open Water Swimmers
San Francisco Bay is home to a thriving open water swimming community, with daily swims happening for over 150 years. Yet, the myth of “shark-infested waters” persists—thanks to Hollywood, Alcatraz folklore, and commercial marketing.
The reality? While sharks exist in the Bay, the ones commonly found here are small, bottom-dwelling species rarely seen by swimmers. Generations of experienced swimmers—including our team at Pacific Open Water Swim Co.—have spent decades in these waters without a single confirmed white shark encounter.
What Sharks Are Found in San Francisco Bay?
Most sharks in the Bay are harmless bottom-feeders that pose no known risk to swimmers:
- Leopard Sharks – The most common shark in San Francisco Bay, typically 2 to 3 feet (0.6 to 1 meter) long. These harmless fish feed on crustaceans and small fish.
- Sevengill Sharks – Occasionally present in the Bay but mostly in deeper waters. These scavengers prefer fish and rays over anything else.
- Thresher Sharks – Rarely seen, these sharks stay in deep water and avoid human interaction.
What about Great White Sharks? While white sharks are frequent along the California coast but not commonly found inside the Bay. Their primary prey—seals and sea lions—are more abundant offshore near the Farallon Islands.
In over a century of daily swimming, no white shark attacks on swimmers have ever been recorded inside San Francisco Bay.
Debunking the “Shark-Infested Waters” Myth
The myth of shark-infested waters comes from a mix of:
- Alcatraz prison authorities, who exaggerated the risk to discourage escape attempts.
- Movies & TV (including Shark Week specials), which sensationalize the idea.
- Alcatraz tourism & large group swim marketing, which lean into the legend for dramatic effect.
The truth? Thousands of swimmers enter the Bay every year without incident. The real risks in open water swimming are currents, cold water, and fatigue—not sharks.
Wildlife Encounters: What Swimmers May Actually See
While shark encounters are virtually nonexistent, swimmers frequently see other marine life, including:
- Harbor Porpoises – Small, shy marine mammals that have made a strong return to the Bay in recent years.
- Whales (Gray & Humpback) – Occasionally migrate into the Bay in spring and fall.
- Seals and sea Lions – They typically keep their distance, though some sea lions have interacted with swimmers in rare cases.
Between 2019 and 2022, a few isolated sea lion bites were reported at Aquatic Park, likely due to territorial behavior or illness. However, all injuries were minor and resolved without long-term complications.
How We Prioritize Safety at Pacific Open Water Swim Co.
At Pacific Open Water Swim Co., we’ve spent over 22 years swimming in the Bay, leading thousands of swimmers safely through Alcatraz crossings and other open water adventures.
Our safety measures include:
- Daily Marine Condition Assessments – Monitoring tides, currents, and conditions.
- Escort Support – USCG-licensed captains coordinating with local maritime authorities.
- Marine Life Awareness – Educating swimmers on what to expect and how to interact responsibly.
Final Thought: The Bay Is Open for Swimmers
San Francisco Bay has been a safe and thriving open water swimming destination for over a century. While no open water environment is entirely risk-free, the long history of swimming here proves that marine life encounters are exceedingly rare.
Want the full breakdown of historical data, shark behavior, and expert insights? Read the complete article here: Sharks in San Francisco Bay: Myths, Facts & Safety for Swimmers