If you thrive on the thrill of a crowd at the beach, theme park or other such place, don't miss the 4th of July, one of the most crowded days of the year at California's beaches and theme parks. For tourists visiting from less populated places, the effect of millions of people converging into one space can be exciting-an experience of a lifetime. However, normally placid travelers are surprised to discover that their phobias and fears swell up with the site of a crowd, and they may suddenly feel trapped.

Phobias that can rear their heads unexpectedly include agoraphobia, a fear of having a panic attack or panic-like symptoms in a situation that is perceived to be difficult to escape from. Approx. 3.2 million adults in the US (2.2% of the population) suffer from agoraphobia. Demophobia, an exaggerated or irrational fear of crowds; enochlophobia, or the fear of crowds; and ochlophobia that includes fears of crowds and fear of being trampled in a crowd, all can be based in real life events that have occurred in crowd situations, and usually make headlines in the news.

Extremely crowded events can be stressful for anyone, but there is no reason that you should not enjoy once in a lifetime opportunities. Thoroughly plan and prepare for your trip, have at least one backup plan, travel with supportive companions, know your triggers and remove yourself from any situation that you can't handle.

Places where you are guaranteed to find crowds this summer in California include special days: 4th of July, concerts & events, and Labor Day Weekend. These days are the top attended and most crowded summer days in the state's urban areas, especially the beach.

Shown in the photos: Huntington Beach, Calif. — It's hard to believe that the normally mellow residential town of around 200,000 can swell to a million or more people at any given time, but annual traditions such as 4th of July, and U.S. Open of Surfing are no hidden secret, and those who know the scene arrive early (around 8 a.m.) when there's still beach parking and maybe even a bonfire pit to stake out. As the crowds swell, the beach bike path traffic is so thick that its flashing lights remain in a constant state of yellow, warning pedestrians and bicyclists to proceed with caution. Lifeguards rope off and create small freeways on the beach so that they can get their vehicles safely in and out of the crowds.

Other (guaranteed) crowded places on the 4th of July include all San Diego beaches; Los Angeles beaches — Long Beach, Hermosa, Redondo, Manhattan, Marina del Rey, Santa Monica, Malibu and Dockweiler; San Francisco beaches and attractions such Pier 39, Alcatraz, Universal Studios, San Diego Zoo, Sea World, Disneyland and major cities where free fireworks displays are advertised.

The GOOD: Great crowds, sunshine, energy, excitement, anything goes, entertainment, ample photo opportunities

The BAD: Overcrowding, lack of parking, hour-long to several hour waits to get out of the traffic jams, long waits for bathrooms, long waits for food, walk long distances, potential parking tickets

While humans seeking crowds at California's beaches have been compared to lemmings rushing to the sea, scientists claim to have dispelled a myth that the little creatures (lemmings) are committing suicide. The famous rodents are driven by strong biological urges as they migrate in large groups when population density becomes too great. They sometimes choose to cross a body of water in search of a new habitat, and many drown if the body of water is so wide as to stretch their physical capability to the limit, so the theory goes. Fortunately there's no phobia that describes the fear of humans rushing into the sea en masse, but if you suffer from such fears, it might be best to avoid crowded beaches on the 4th of July.