Located in the Nanshan Cultural Tourist Zone of China's Hainan Province, the Sanya Nanshan Treehouse Resort is one of the most impressive tree house resorts in the world. Four very large and elaborate tree houses that are suspended in the branches of large, old tamarind trees are offered as vacation rentals here. The largest tree house on site is the Big Beach in the Sky, a two-story tree house that sleeps six and is only accessible via a rope bridge that is connected to another large tree house. On the beach, there are more tree house accommodations for up to 20 people. American architect David Greenberg was the guiding force behind the enormous tree houses, and he built them using natural materials to reflect their surroundings [source: Li].