California beaches are generally safe to swim, but safety varies dramatically based on water quality and ocean conditions. From a health perspective, the "72-hour rule" is vital: you should never swim in the ocean for at least three days after it rains. Stormwater runoff carries bacteria, chemicals, and debris from city streets directly into the surf, often causing bacteria levels to spike well above safety limits. Organizations like "Heal the Bay" provide daily "Beach Report Cards" that you should check before heading out. Physically, the greatest danger is rip currents, which are powerful channels of water flowing away from the shore. In 2026, lifeguards are increasingly using drone technology to spot these from above. If you get caught in one, stay calm and swim parallel to the shore until you are out of the current. Additionally, be aware of the "Great White" shark activity which has seen a slight increase in sightings off the Central and Southern California coast, though actual attacks remain statistically infinitesimal. To stay safe, always swim near a staffed lifeguard tower and pay attention to posted warning signs regarding surf height and water contamination.