Beaches are great places to check out your fellow human beings in all their infinite variety, says Dr. Aaron Wolfgang, a professor emeritus of psychology who wrote a book called "Everybody's Guide to People Watching." "The great thing about people-watching and beaches is that people are themselves. It's a playful activity so you're getting more naturalistic activity," he says.

Wolfgang, who has visited beaches all over the world, selects some of the best for indulging in the pastime of people-watching:

In the United States, he likes Venice Beach, California:

"That is probably, on Sunday mornings, one of the most unusual places I've ever seen in my life. People sing to you, play guitars, there are jugglers. There is more variety of activity than any other beach I've ever seen."

Outside the United States, he likes Copacabana Beach in Brazil, which he says is interesting for people showing off the latest beach styles.

"It's interesting for its parade. There is a very ostentatious display of body there. People are always playing paddle games, like tennis." But he warns it can be dangerous: "In daylight, you can be mugged."