Summer is just beginning, and hikers will soon be strapping on their packs and getting ready to hit the trails. If the past is any indicator, thousands will need to be rescued. At Yosemite National Park alone, the search and rescue team responds to 300 incidents a year, nearly one a day.

How can hikers boost their odds of having a good time without needing the rescue team? Well, packing a little smarter is a good place to start.

Many hikers don't pack properly. They leave out essential items, a study of hikers in New Hampshire's White Mountain National Forest found. Young and inexperienced hikers were the worst offenders.

Experienced hikers know that cell phones have little or no reception within the park. Even dedicated GPS receivers sometimes fail there.

Only about 40% of the nearly 200 hikers surveyed packed 8 or more of 10 essential items, the study authors' cutoff point for preparedness. The items most frequently left out were a compass (54%), whistle (57%) and fire starter (48%).

The 10 items people should pack for hikes in the White Mountains, as recommended by New Hampshire's HikeSafe Program are: a map, a compass, extra clothes, rain gear, a fire starter, a flashlight, extra food and water, a knife, a first aid kit, and a whistle. Only one out of every six hikers in the study packed all 10.

The most common reason for leaving out items was that hikers were only going out for a short summer hike. But too often, a wrong turn or sudden change in weather can turn a short hike into a much longer and uglier one.

The second most common reason for not packing items was simple forgetfulness. Only nine of 167 hikers said that they did not own the unpacked equipment.

Perhaps another reason so many hikers neglected to pack a compass was that they believed they could rely on some form of GPS technology, usually a GPS-enabled cell phone. But experienced hikers know that these have little or no reception within the park. Even dedicated GPS receivers sometimes fail there.

While other parts of the country might require slightly different equipment for a safe hike, such as a mirror, having the proper equipment is vital for safe and happy hiking, as well as for other outdoor activities, from biking to boating.

When enjoying the great outdoors, it's best to take a page from the Girl — and Boy — Scouts: Be prepared.

The study was published online before print by Wilderness & Environmental Medicine.