There are three trailheads that give you access to the area:
First is Sand Hollow State Park. Just enter the park (don’t forget to pay the entrance fee), drive through “tunnel,” and enjoy!
The second trailhead is is from the town of Washington, Utah, which you can access from the I-15, by taking exit 10, where you’ll turn left on Telegraph, right on Washington Field Road, and left on Washington Dam Road. Follow Washington Dam road until it turns to dirt. Drive up and over the only hill and at the bottom; you’ll be at the Washington Dam Trailhead. Look for the “Adopted by the Utah 4×4 Club” signs. Turn right and look for the steep, technical road that leads up onto the dunes. This access is free.
The third access is through the town of Hurricane, Utah. From I-15, take exit 16 to Hurricane City. Turn right onto 700 West, and take another right onto 2060 South. The road turns to gravel. Travel 2.2 miles and turn right where the road forks onto Warner Valley road (there will be a sign). Follow this road up onto the dunes. This access is free.
The Sand Hollow, or the Sand Mountain OHV area is a stunning and fun place to ride. You’ll find miles of soft, red dirt trails, as well as varying technical difficulty on slick sandstone, plus several sand dunes, sand whoops, and washes. On top of Sand Mountain, you’ll be compelled to stop and appreciate the breathtaking views of St. George, the Hurricane Cliffs, the Arizona Strip, the Pine Valley mountains, and the Red Cliffs National Conservation Area.
Note for the sand dunes: The BLM has an agreement with the Sand Hollow Park that includes having the Park Rangers patrol the dunes. When operating on sand dunes a red or orange safety flag attached to the vehicle, at least 8 feet above the surface of level ground, is required.