National Parks are not immune from crime. We recommend that people use precautions as they would anywhere.'' Within the last 10 years, there have been no visitor homicides inside the park. More worrisome than crime, Cowles says, is the sheer volume of visitors who are unfamiliar with being in a wilderness area and don't know proper behavior. The visitor who is reckless on the trail or dives into a river for a swim above a waterfall creates hazards for himself. At least once a year someone jumps into an inviting pool, gets caught in the current and goes plummeting over the falls.
Most problems are minor.
Park rangers' most common rescues involve dehydrated hikers who did not carry water, or those who sprained ankles. Tourism increases as the season warms, and the valley can quickly turn to gridlock. It's a good idea to arrive before 9 a.m. on those days,'' Cowles suggests. In the past two decades, annual visitation has doubled. The system runs efficiently and has helped protect the park's natural habitat.