Introduction to the Happy Main Line: The Happy Main Line is a world-class and the first unmanned aerial sightseeing train in the country. It has a total distance of 3.88 kilometers and runs at a constant speed over the OCT tourist resort, giving tourists an unprecedented visual experience. Along the way, you can visit the famous Shenzhen Happy Valley, Window of the World, Splendid China, China Folk Culture Village and Shenzhen Bay at high altitude.