What's one of the most popular vacation spots anywhere? If you guessed the beach, you'd be right. People from all over the world love to go to the beach. People will travel hundreds, even thousands, of miles to find a nice bit of sand by the ocean. People love to swim in the ocean or just lie in the sun and read a book.
During the summer, beaches all over the United States are crowded with vacationers. There's some trouble that comes with all those vacationers. There is extra traffic. There is more pollution. There is damage to the beaches from all those people walking all over them.
And there's litter.