From spots along either rim of the Grand Canyon, it is possible to glimpse the swirling Colorado River, more than 5,000 feet below. Still carving its way slowly through the surrounding limestone and sandstone walls after millions of years, the Colorado has created one of the world's most awe-inspiring natural attractions.

The Grand Canyon is far too vast to be experienced from any one place. Guests who wish to fully understand the canyon may view it from lookouts along the South or North Rims, hike from the rims down to the river, take a rafting excursion along the river, hire a helicopter to give an eagles-eye view from above, or do any of these in combination. But most people simply drive to the South Rim and walk out along the Rim Trail, pausing every few moments to take it all in.

The South Rim, accessible from Highway 64 from Williams and Flagstaff, Arizona, is open 24 hours a day, 365 days a year. A visitor center and many amenities are available, including four hotels: The Bright Angel, The El Tovar Hotel, the Kachina Lodge and the Thunderbird Lodge. There is also overnight camping in Mather Campgrounds. Most of all, the South Rim is equipped to handle the hordes of tourists who arrive during summer months.

The North Rim has a completely different feel: it offers services from mid-May to mid-October only, while giving a uniquely pristine view of the canyon, without the sea of tourists swarming the South Rim. Also, the venerable Grand Canyon Lodge is at the North Rim, carved out of stone at the very edge of the canyon. Every tourist must find the time to sit down in the great room of the lodge and stare into the canyon through floor-to-ceiling picture windows. Between October and May, the North Rim is open for day use only, as the road from Jacob Lake to the North Rim (Highway 67) is subject to closure with little or no notice during winter.

Visitors in good shape can take a two-day hike to the river and back from the South Rim -- the hike from the North Rim takes longer. It is a memorable experience, but remember: The second day is all uphill. River raft excursions are available through the National Park Service and from private companies, and can vary anywhere from three to 21 days. There are also half-day and one-day water trips, but these often do not take place within the boundaries of Grand Canyon National Park. Many people from as far away as Las Vegas enjoy dropping down into the canyon on a helicopter tour. Private companies offer different length tours at varying prices. No one who has ever seen Grand Canyon from the air has ever forgotten it.

A few words to the wise: The best light for viewing and photographing the canyon is early morning and late afternoon. Also, when planning a trip, bear in mind that the South Rim is at 7,000 feet altitude, and the North Rim at 8,000 feet. Even walking can be strenuous at this elevation, so plan accordingly. -- Doug Konecky