The pristine forested area, the last bastion of the Dong Phaya Yen Forest, is one of Thailand’s most important watersheds, giving rise to hundreds of creeks and streams. From its source, Sai Yai River flows into the Prachin Buri River and converges with the Nakhon Nayok River downstream to form the Banpakong River.

Beyond a wild white-water ride or an exhilarating river adventure, the breathtaking landscape that hugs the river is home to a great diversity of spectacular flora and fauna; river-rafting unveils some fascinating and rarely seen spectacles – butterflies hovering over a salt lick by the river; colourful birds seeking refuge in the forested canopy.

Riding the rapids at Kaeng Hin Phoeng is only possible during the rainy season when rivers and streams, fed by heavy rainfall and run-off from the mountains, are in full flow. Rocky cliffs towering over the upper reaches of the Sai Yai River force raging waters into a narrow trench. A wall of water builds up before it surges downstream. In the middle section, an eroded river-bed is dotted with rocky outcrops. In the rainy season, torrential flows of water cascade over these scattered islets giving rise to cataracts. The raging river, characterised by hydraulics, reverse eddies, spiral waves and other white-water challenges, will not disappoint.

The white-water rafting trip on the Sai Yai River starts a short distance above the Kaeng Hin Phoeng rapids and continues past Greater Kaeng Hin Phoeng, a 100-metre stretch of the river with swirling waves forging their way through rocky crevices.

The whitewater classification for Kaeng Hin Phoeng rapids ranges from Class 3 to 5, or from intermediate to expert level of white-water navigating skills and experience and requires extreme caution. The trip features six rapids – Kaeng Hin Phoeng, Kaeng Wang Nam Lom, Kaeng Wang Bon, Kaeng Luuk Seua, Kaeng Wang Sai and Kaeng Ngu Hao.

Kaeng Wang Nam Lom is named after phak nam (Lasia spinosa), vegetation that grows in the wide stretch of the rapids. At the end of the stretch, water is forced through rocky islets and form a 40-50 metre long Class 2 cataract.

Kaeng Luuk Seua, a Class 3 rapid, is a 60-metre stretch of the river characterised by torrential currents, the impact of which is intensified by rocky outcrops in the mid-stream.

At Kaeng Wang Bon, a minor rapid, powerful V-shaped waves frequently steer rubber rafts right into a mesh of bushes and protruding branches that line the banks of the river. While at Kaeng Wang Sai, rocky mounds of various sizes scattered throughout this 80-metre section of the river generate undulating waves. It takes sheer dexterity to steer the craft whilst dodging the obstacle course.

First timers are required to attend a briefing conducted by certified and highly experienced instructors before embarking on the rafting trip. The journey from Kaeng Hin Phoeng to Kaeng Wang Sai, takes approximately 1 to 2 hours.

International Grading System Whitewater Classification

• Class 1 – Easy
  The easiest and safest level with fast moving water, ripples and small waves with few obstructions, all obvious. Easily rescued
  
  
• Class 2 – Novice
  Straightforward rapids with wide clear channels evident without scouting. Rocks and medium-sized waves easily missed by trained paddlers. Easily rescued.
  
  
• Class 3 – Intermediate
  Rapids with moderate and irregular waves. Strong eddies and powerful currents, particularly on large volume rivers. Good boat control is required in tight passages and around ledges. Scouting is advisable. Rescue is possible.
  
  
• Class 4 – Advanced
  Intense, powerful but predictable rapids. Many feature large unavoidable waves, holes and constricted passages demanding fast manoeuvring under pressure. Scouting is necessary first time. Difficult rescue may be possible.
  
  
• Class 5 – Expert
  Extremely long, obstructed or violent rapids which expose a paddler to above average danger. Drops may contain large unavoidable waves or holes. Rapids may continue for long distances between pools, requiring a level of fitness. Scouting is essential but difficult. Difficult and painful rescue may be possible.

Safety Measures
There are lifeguard stations at all six rapids — Kaeng Hin Phoeng, Kaeng Wang Nam Lom, Kaeng Wang Bon, Kaeng Luuk Seua, Kaeng Wang Sai and Kaeng Ngu Hao. Each is staffed by certified, highly skilled and experienced personnel and stocked with supplies of life jackets, ropes and other essential items for rapid response rescue operations.

Rafting Fees
The trip is made in an inflatable rubber raft.
450 baht per person or 3,500 baht per rubber raft for 8 persons

Getting to Kaeng Hin Phoeng
From Bangkok, take Suwannasorn Road and Highway 33 and head for Kabin Buri district. Look out for the 201 km marker with a petrol station and Wat Sra Du School to the left. Continue along Sra Du-Sapan Hin Road for 16 kms then turn left and drive 17 kms to get to Ban Nong Haen School. Turn left and continue for another 7 kms to get to Khao Yai Ranger Station No. 9. From this point, continue for another 8 kms, then hike 2.5 kms along a forest trek.

RAFTING OR KAYAKING ON THE NAKHON NAYOK RIVER
Whitewater Classification: Class 1 – 3
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Contact information
TAT Central Region Office – Region 8
Areas of responsibility: Nakhon Nayok, Sa Kaeo, Prachin Buri and Chachoengsao
Tel: 037 312282, 312284
Fax: 037 312286
E-mail: tatnayok@tat.or.th