Heo sai Waterfall is located within Nam Nao National Park, one of the important watershed forests of the upper northeastern and lower northern regions of Thailand. This waterfall is a famous natural tourist attraction in Phetchabun Province, characterized by water cascading down a large sandstone cliff into a pool below, amidst a remarkably lush rainforest. Along the walking path to the waterfall, visitors will experience a natural forest environment filled with large trees, vines, ferns, mosses, and dense undergrowth, creating a humid and cool atmosphere throughout the day. This is especially true during the rainy and winter seasons when the forest is vibrantly green and covered in a light mist in the mornings.

The waterfall is formed by the Huai Sanam Sai stream, which originates in a dense forest area called "Dong Naeng," before flowing through the Sam Phak Khaw forest and cascading down large sandstone cliffs to create Heo Tsai Waterfall. This stream is also geographically significant as it forms a natural boundary between Nam Nao District in Phetchabun Province and Khon San District in Chaiyaphum Province, before flowing into the Mae Choen River and connecting to the Phong River basin in the northeast. Therefore, the ecosystem in this area is highly abundant and complete. The area boasts diverse forests, water resources, and wildlife. Tourists may spot various bird species, butterflies, and small animals that inhabit this humid forest area along the nature trail.

The most striking feature of Haew Sai Waterfall is its approximately 20-meter-high sandstone cliff, the source of a continuous stream of water. Especially during the late rainy season, the water volume is high, crashing against the rocks with a resounding roar. The mist surrounding the pool below adds to the refreshing atmosphere. Below the waterfall are large, naturally formed rocks and cliffs, some providing shelter from the rain or beautiful viewpoints. It's also a popular spot for nature photography, as the combination of the waterfall, cliffs, and surrounding rainforest is pristine, creating a feeling of being in a deep forest.

Accessing Haew Sai Waterfall is another significant attraction. Tourists must hike from the main entrance at kilometer 67 on Highway 12 (Lom Sak – Chum Phae) along a nature trail for approximately 1 kilometer. The trail is mostly dirt and natural rock formations, with both flat and slightly sloping sections, allowing visitors to experience the forest up close. Along the way, you'll hear the sounds of flowing water, wild birdsong, and the scent of damp earth from the rainforest, creating a lighthearted adventure atmosphere. It's perfect for those who enjoy hiking, nature study, and ecotourism, especially during the rainy season when the sides of the trail are lush green with vegetation and moss beautifully covering the rocks.

Near Haew Sai Waterfall, there are several other natural waterfalls within Nam Nao National Park, such as Sai Thong Waterfall, Sai Kaeo Waterfall, and Sai Ngern Waterfall, which are interconnected by nature trails. Sai Thong Waterfall, in particular, is located approximately 500 meters to 1.3 kilometers away (depending on the source), a wide waterfall with a shady atmosphere ideal for relaxation. This makes it a popular destination for tourists who plan day trips to explore multiple natural points. Additionally, the surrounding area offers campsites, viewpoints, and stargazing trails during the winter months, making Nam Nao National Park one of the most popular natural destinations in Phetchabun Province.

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How to Get There

• From the Nam Nao National Park Visitor Center (along Highway 12, Lom Sak-Chum Phae route), drive to the parking area at Kilometer 67. From there, visitors must hike along a nature trail for about 1 kilometer to reach the waterfall. The trail consists of dirt paths and rocky terrain with some steep slopes; sturdy footwear is highly recommended.

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Travel Tips

• Visit during late rainy season to early winter for the best waterfall scenery.

• Start your trip early to allow enough hiking and return time before dark.

• Wear hiking or non-slip shoes for safer trekking conditions.

• Carry enough drinking water since there are no shops along the trail.

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Admission Fees:

• Thai Citizens: Adults 40 THB, Children 20 THB

• Foreigners: Adults 200 THB, Children 100 THB (Additional fees apply for vehicles)

Opening Hours:

• Open daily from 08:00 AM – 04:30 PM. (Visitors should plan their return hike before sunset).