Thanarat Waterfall is a hidden gem nestled within Khao Yai National Park, the first national park in Thailand, which spans four provinces: Saraburi, Nakhon Ratchasima, Prachinburi, and Nakhon Nayok, covering an area of approximately 1.36 million rai. Traveling to Khao Yai National Park offers more than just breathtaking natural landscapes. The park is adorned with various types of forests, including deciduous forests, dry and moist tropical forests, alpine forests, grasslands, and secondary forests formed from shifting agriculture. It is also a vital source of many major rivers, such as the Prachinburi River, Nakhon Nayok River, Bang Pakong River, Lam Takong River, and Phra Phloeng River, making it a thriving habitat for a diverse range of wildlife, including deer, elephants, tigers, banteng, serow, bears, gibbons, hedgehogs, civets, wild rabbits, and numerous species of birds and insects. The park is equipped with various attractions that cater to recreational activities, whether it be wildlife watching, birdwatching, swimming in waterfalls, enjoying scenic views, rafting, short or long hikes, and even rock climbing. Particularly at Thanarat Waterfall, the area beneath the falls features a wide valley with multi-tiered cascades and fields of wildflowers that bloom during the flower season. However, this valley lacks hiking trails, making access quite challenging. One of the most popular activities here is rappelling down the cliffs, which can reach heights of several hundred meters and includes four levels, each with different steepness and height. This thrilling adventure is a true test of courage for tourists who seek excitement and challenge in their travels.