Southwest of Lihue and northeast of Poipu on Kauai, the private Kipu Ranch has a nine mile ATV route. The route is only accessible via guided tour, but the lands are truly spectacular (used for filming jungle scenes in Jurassic Park and Raiders of the Lost Ark).
Kipu Ranch Adventures has a permit to guide ATV tours on the ranch lands. They rent ATV and provide helmets. This is very beginner level riding and they provide excellent beginner instruction. Note: experienced riders may be quite bored with the frequent and lengthy stops.
To reach the trailhead from Lihue, head south on SR50 for 3 miles. Turn left heading south on Kipu Road and veer to the right. Continue for about a mile and follow the signs.
Overall, Kipu Ranch is the 1st most popular ATV riding trail of all 10 ATV trails in Hawaii.