Millions of people come to national parks each year to enjoy the splendors of wildlife and natural beauty, but a tiny fraction arrive with a grim agenda.

So far this year, at least 18 people have committed suicide in America's national parks -- including one in Colorado.

In May, searchers found the body of a 27-year-old man who drove into Colorado National Monument near Grand Junction, parked on the side of a road, walked about 200 yards away and shot himself.

And last October, at the same park, a 57-year-old woman drove her station wagon off a 250-foot cliff. A few weeks later, a 63-year-old man drove to an overlook at the park, sat on a rock outcropping overlooking a valley and shot himself.

Colorado National Monument superintendent Joan Anzelmo says the staff is doing everything it can to prevent suicides.

Lanny Berman, the executive director of the American Association of Suicidology, says that when it comes to suicides in national parks, in general, the driving force for most is availability and accessibility and, secondarily, whether that site offers something that other sites don't.