Kauai has many stunning natural features, but the largest, and most spectacular is Waimea Canyon, otherwise known as the Grand Canyon of the Pacific. As the canyon is over fourteen miles long, and over 3,600 feet deep, it is definitely one of the geologic wonders of the world. The canyon was carved by the Waimea River, which has flowed down to the ocean from Mount Wai'ale'ale over thousands of years. (More information on the geologic history of Waimea Canyon is located here). In my opinion, visitors to Waimea Canyon, like the Grand Canyon should get out and explore the area on foot, but for those who either don't have the time, or the ability to do so, this overlook provides stunning views for everyone; and serves as a great panoramic vista even for people who plan on hiking.
Directions: The overlook is located directly in Waimea Canyon State Park, which adjoins Koke'e State Park. The overlook is well signed, and located directly off of Highway 550 (Koke'e Road), 11.1 miles North of Kekaha. From the parking area, there is a short (.1) paved interpretive path that traverses around the Canyon's edge.
Tips: Waimea Canyon is located on a part of Kauai that is one of the wettest areas on the planet. Correspondingly, the view may not look like the sunny day I experienced above. Be sure to plan accordingly for rain if you do visit the Lookout, and be sure to take your time to fully appreciate the view.