For those of you who want some real Colorado adventure, whitewater rafting is just your activity.

More than just an adrenaline rush, whitewater rafting is one of the best ways to see and enjoy Colorado. As you are venturing into the unknown, start out small and work your way up. No matter what part of the state you choose, there are experienced whitewater rafting companies ready to serve you. Only those who are experienced should navigate on their own. Every year people are killed rafting. Most of them are inexperienced.

Generally, there are five levels of whitewater rafting you can enjoy in Colorado. Those levels range from Class I to Class V. Most tourists who value their lives will not venture beyond a Class V.

Class I rapids are easy, with riffles and small waves, few obstacles and clear sailing. Class II rapids are for novices, still straightforward but with medium-sized waves. Class III rapids are for intermediates, with more difficult rapids, a strong current and some obstacles that can be avoided pretty easily. Class IV, for advanced rafters, have intense but predictable rapids and may have some unavoidable waves and holes. Class V, is only for experts and may have long or violent rapids, unavoidable holes and waves, obstacles that may be difficult to avoid, and large drops. Class VI may be unpredictable, extremely difficult to dangerous, and should be undertaken only by expert rafters who are in very good condition.

There is hardly a more exhilarating activity than enjoying one of the 13 river systems across the state of Colorado. When picking a tour guide do not always assume they are experienced and knowledgeable. Many are not. Most "river rats" make less than $8 an hour plus tips and are prone to living a partying lifestyle. Before you get on a raft, ask the whitewater tour company who your guide is going to be and their level of qualifications. Raft guides in Colorado have to be certified. That's not true in all states.

Unless you are experienced, it's best to go with a guide company who will know the river and use equipment that is regularly inspected and repaired. The state of Colorado licenses dozens of outfitters, who operate on 13 river systems across the state.

The most popular river for rafting is the Arkansas, which has its headwaters on Mount Democrat near Leadville and drops 10,000 feet in 125 miles (to Pueblo), where it continues through southeast Colorado, across Kansas, and eventually into the Mississippi River. The river includes almost all classes of rapids, depending upon which section you tackle. One of the most exciting is through the Royal Gorge near Canon City. The Arkansas River flows right through Buena Vista - one of the most beautiful cities in the Colorado Rockies.

Other popular Colorado whitewater spots include the Colorado River, through Glenwood Canyon and down to Grand Junction, near the Utah border; the Green River, which bisects remote Dinosaur National Monument; and the Dolores River in southwest Colorado. Popular with Front Range rafters are Clear Creek, which comes crashing out of Summit County, and the South Platte, a good waterway for beginners or those who don't want to work very hard. Rockies.com readers have been enthralled with the upper and lower Animas rivers in Durango, Colorado.

Guide companies offer not only the rafting experience itself, but also a variety of related adventures, from a picnic to the more heart-pounding pounding rock climbing. Many also rent kayaks, for those who want to challenge the rapids one-on-one. And for those of you want to bypass getting a guide, find a safe spot, go to a tire store and get a tube. Tubing a Colorado river is a fantastic high.