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. Overnight visitors have a range of choices for accommodations, depending on how much they want to rough it. Lodging ranges from campgrounds or tent cabins to the famed, luxurious Ahwahnee, which has hosted royalty, heads of state, movie stars and eight American presidents.