Much of Hainan, the island-province off the south coast of the Chinese mainland, is covered by the country's largest rainforest. The Hainan Tropical Rainforest National Park ranks among the world's most vital biodiversity hotspots. Within it lies the Bawangling nature reserve, the sole habitat of one of Earth's rarest primates, the Hainan gibbon. Back in 2003, its population amounted to a dangerously low 13, but in 2025 three newborns brought the number up to 44 thriving individuals. Today, this remarkable primate is the only gibbon species in the world that is witnessing a steady population resurgence.