Where is Sai Yok National Park?

Sai Yok National Park is in Kanchanaburi Province, western Thailand, covering parts of Sai Yok and Thong Pha Phum districts along the Khwae Noi River. The western side of the park meets the Thailand–Myanmar border.

What is Sai Yok National Park famous for?

It is famous for Sai Yok Yai Waterfall, which descends toward the Khwae Noi River, limestone caves such as Lawa Cave and Dao Wadueng Cave, Kitti's hog-nosed bat, river scenery and its World War II Death Railway history.

What is the difference between Sai Yok Yai and Sai Yok Noi waterfalls?

Sai Yok Yai is the signature waterfall of Sai Yok National Park and descends toward the Khwae Noi River. Sai Yok Noi, also called Khao Phang Waterfall, is a smaller, easily accessible waterfall along the main route through Sai Yok District and is a separate stop from the main national park experience.

What is Kitti's hog-nosed bat?

Kitti's hog-nosed bat (Craseonycteris thonglongyai), also called the bumblebee bat, is recognised as the world's smallest mammal by body mass, weighing around 1.5–2 grams. It was discovered in the Sai Yok area in 1973 by Kitti Thonglongya and lives in limestone caves. It is highly sensitive to disturbance.

How far is Hellfire Pass from Sai Yok National Park?

Hellfire Pass is a short drive from the Sai Yok National Park landscape along Highway 323. The Hellfire Pass Interpretive Centre is open 09:00–16:00, with seasonal maintenance and holiday closures.

When is the best time to visit Sai Yok National Park?

November to February is generally the most comfortable time for exploring. May to October brings greener forest and stronger waterfalls but rain can affect trails, caves and river activities. March and April are hot, with lower water levels.

How do I get to Sai Yok National Park?

From Kanchanaburi town, drive northwest along Highway 323 toward Sai Yok and Thong Pha Phum — roughly 100 km depending on your destination in the park. The railway from Kanchanaburi also runs west to Nam Tok along surviving sections of the Thailand–Burma Railway.

Can you stay overnight in Sai Yok National Park?

Yes. The park provides park houses and camping areas, including zones near the park headquarters and the Khwae Noi River, bookable through the Department of National Parks system. Floating and riverside accommodation is also found in the surrounding area.

How large is Sai Yok National Park?

Sai Yok National Park was originally gazetted over approximately 312,500 rai, or about 500 square kilometres. The Department of National Parks has subsequently been working on a legal boundary revision.

How long should I spend at Sai Yok?

One day covers the highlights of nature and history, but two days let you experience the river, caves and Hellfire Pass at a slower pace, ideally with a riverside overnight stay.

Sai Yok National Park, Kanchanaburi | Waterfalls, Caves, Khwae Noi River & Death Railway

Where Nature and History Meet

There are places in Thailand where nature and history are inseparable. Sai Yok National Park is one of them.

Set among the forested mountains of western Kanchanaburi, the park follows the landscape of the Khwae Noi River, where limestone cliffs, waterfalls, caves and dense forest meet one of the most significant historical landscapes of World War II in Thailand.

Here, a waterfall can plunge directly toward the river. A limestone cave can shelter one of the world’s smallest mammals. And deep in the surrounding forest, traces of the Thailand–Burma Railway, commonly known as the Death Railway, remain as reminders of a much darker chapter in the region’s history.

Sai Yok is not simply a waterfall destination. It is a landscape to explore slowly — by river, forest trail, cave and railway history.

Sai Yok at a Glance

~500 km²: 312,500 rai originally gazetted across Sai Yok and Thong Pha Phum.
~1,327 m: Khao Khwae — the park’s highest point.
19th: Thailand’s national park number, gazetted 27 October 1980.
1.5–2 g: Kitti’s hog-nosed bat — the world’s smallest mammal, discovered here.

Official name: Sai Yok National Park
Thai name: อุทยานแห่งชาติไทรโยค
Province: Kanchanaburi
Districts: Sai Yok & Thong Pha Phum
Established: 27 October 1980 · Thailand’s 19th national park
Gazetted area: 312,500 rai · approximately 500 km²
Highest point: Khao Khwae — approximately 1,327 m
Landscape: Mountains, limestone terrain, forest, caves & the Khwae Noi River
Signature experiences: Waterfalls, caves, river landscapes, wildlife & World War II heritage

Why Sai Yok Is Special

Sai Yok has a character very different from Thailand’s high-altitude mountain parks. Its identity comes from the relationship between river, forest and limestone.

The Khwae Noi River passes through the protected landscape, while mountain ranges rise on either side. Most of the terrain lies at roughly 300–600 metres above sea level, but the park rises considerably higher in the surrounding mountains, with Khao Khwae reaching approximately 1,327 metres. The western side of the park meets the Thailand–Myanmar border.

A remarkably varied landscape

Limestone caves
Forest-covered mountains
River valleys
Waterfalls
Natural streams
Wildlife habitat
Historical railway remains
Former World War II sites

The attraction is not one single viewpoint. Sai Yok works best as a landscape journey.

The Khwae Noi River

The river that gives Sai Yok its rhythm

The Khwae Noi River is one of the defining features of Sai Yok. Rather than simply passing beside the park, the river is deeply integrated into its landscape and history. Numerous streams and tributaries descend from the surrounding mountains and feed the river system.

The river also provides the setting for one of Sai Yok’s most distinctive travel experiences: seeing the forest from the water. River journeys and floating accommodation are particularly associated with this part of Kanchanaburi, letting visitors experience the limestone hills and forested banks from a completely different perspective.

This is one of the places where the journey itself is part of the destination.

Sai Yok Yai Waterfall

A waterfall that meets the river

Sai Yok Yai Waterfall is one of the park’s signature natural landmarks. Unlike many Thai waterfalls that fall into an inland pool, Sai Yok Yai descends toward the Khwae Noi River, creating an unusually intimate relationship between waterfall and river landscape.

The surrounding forest and limestone scenery make the waterfall particularly atmospheric during periods of stronger flow. The experience is less about standing in front of a huge vertical cascade and more about seeing water, forest and river occupy the same landscape.

Best for

Nature photography
Riverside scenery
Forest atmosphere
Combining with a river excursion
A relaxed stop rather than a strenuous hike

Water levels vary considerably with rainfall and season, so the character of the waterfall changes throughout the year.

Sai Yok Noi Waterfall

Also known as Khao Phang Waterfall

Sai Yok Noi Waterfall, also called Khao Phang Waterfall, is another famous waterfall associated with the Sai Yok area. It sits along the main route through Sai Yok and is particularly accessible for travellers exploring Kanchanaburi by road or railway.

It is much smaller in scale than Thailand’s major multi-tier waterfalls, but its accessibility and setting have made it a popular stop on the way deeper into western Kanchanaburi.

Limestone Caves

A hidden world beneath the forest

Sai Yok’s limestone landscape creates another of the park’s defining characteristics: caves. Several cave systems occur within the park and surrounding protected landscape, from relatively accessible caves to deeper chambers decorated with stalactites and stalagmites.

Tham Lawa · Lawa Cave

One of the most impressive cave systems associated with Sai Yok. Lawa Cave extends for approximately 500 metres and contains several large chambers of stalactites and stalagmites.

Instead of wide open landscapes, you enter a dark limestone environment shaped slowly by water over geological time — ideal for travellers interested in karst geology, cave formations, photography and natural history.

Tham Dao Wadueng

Dao Wadueng Cave contains multiple chambers with stalactite and stalagmite formations. Earlier exploration records describe approximately eight chambers, making it rewarding for travellers who want to go beyond the park’s better-known waterfalls.

Access conditions can vary. Cave visits should always follow current instructions from park staff.

The World’s Smallest Mammal

Kitti’s hog-nosed bat · Craseonycteris thonglongyai

One of Sai Yok’s most remarkable biological stories concerns an animal that is almost impossibly small. Kitti’s hog-nosed bat, commonly known as the bumblebee bat, is recognised as the world’s smallest mammal by body mass.

The species was discovered in the Sai Yok area in 1973 by Kitti Thonglongya, and the park’s limestone caves became closely associated with its scientific story.

1.5–2 g: Approximate body weight.
2.5–3 cm: Approximate body length.
1973: Discovered in the Sai Yok area by Kitti Thonglongya.

It has a distinctive pig-like nose and lives in limestone cave environments. This is not an animal to be treated as a tourist attraction: the species is extremely sensitive to disturbance. Never enter restricted areas, attempt to capture bats, shine powerful lights at animals or interfere with cave colonies.

A seemingly ordinary limestone cave can contain an extraordinary piece of natural history.

Forest & Wildlife

Sai Yok forms part of the larger Western Forest Complex, one of Thailand’s most important connected forest landscapes. The park contains a mix of forest types associated with the western Thai mountains, including mixed deciduous and dry evergreen forest, bamboo and areas of teak.

The landscape provides habitat for mammals, birds, reptiles, amphibians and freshwater species. Recorded wildlife includes:

Sambar deer
Barking deer
Wild boar
Gibbons
Porcupines
Slow lorises
Serow
Civets
Forest birds
Freshwater fish

Large mammals may occur in the wider forest complex, but sightings are never guaranteed. Sai Yok should be approached as a protected ecosystem rather than a conventional wildlife-viewing park.

The Death Railway Landscape

Where nature meets wartime history

Sai Yok’s landscape cannot be separated from the history of the Thailand–Burma Railway, built during World War II under Japanese military control. Sections of the route passed through the Sai Yok region alongside the Khwae Noi River.

Construction involved Allied prisoners of war and large numbers of Asian forced labourers. Conditions were extremely harsh, with disease, malnutrition, exhaustion and violence contributing to enormous loss of life.

Within and around the park are surviving traces of this history, including railway remains and evidence of wartime camps. The Department of National Parks specifically identifies the World War II railway route and surviving Japanese wartime structures as part of Sai Yok’s historical significance.

Hellfire Pass

A short drive from the national park landscape

Hellfire Pass is one of the most important World War II heritage sites in the Sai Yok area. The Hellfire Pass Interpretive Centre preserves the history of the railway cutting known as Konyu Cutting, where Allied prisoners of war and Asian labourers were forced to cut a passage through solid rock under brutal conditions.

The name “Hellfire Pass” came from the appearance of the site at night, when workers laboured under torch and firelight. Today the centre provides historical interpretation, personal stories and an audio-guided walking trail along original sections of the railway route.

It is not simply another tourist attraction. It is a memorial landscape.

Approach it respectfully and allow time to understand the human history before walking the trail.

A Royal Connection to Sai Yok

Sai Yok’s fame predates modern tourism. During the reign of King Chulalongkorn (Rama V), the royal party visited Sai Yok’s waterfalls.

The beauty of the landscape later inspired Prince Narisara Nuvadtivongse to create the famous Thai musical composition “Khamen Sai Yok” (เขมรไทรโยค).

This cultural connection helped establish Sai Yok as one of Thailand’s celebrated natural landscapes long before national-park tourism became widespread.

What to Do in Sai Yok

Waterfalls: Visit when water levels are favourable and see streams descend toward the Khwae Noi River.
Caves: Lawa and Dao Wadueng reveal another side of the park — geological, dark and far older than the human history around the river.
River: A boat trip or riverside stay offers a different perspective on the forested mountains and limestone.
History: Combine the natural landscape with railway history, surviving railway traces and the Hellfire Pass area.
Wildlife: Birdwatching and quiet forest observation. Birds and small species are a more realistic focus than large mammals.
Stay: Park houses and camping near headquarters and the Khwae Noi River, bookable via the DNP system with equipment rental.

When to Visit

Sai Yok can be visited through much of the year, but each season produces a very different experience.

May–Oct: Green season. Greener forest and stronger waterfalls, though rain can affect trails, cave access and river activities.
Nov–Feb: Cool & dry. More comfortable conditions for exploring, with atmospheric morning light over the river and forest.
Mar–Apr: Hot season. Lower water levels, and exposed areas can become considerably warmer.

How to Get There

Sai Yok National Park is in Kanchanaburi Province, western Thailand, roughly 100 km northwest of Kanchanaburi town depending on your destination within the park. For most international travellers, a private car, rental car or organised day or overnight trip is the most practical option.

By road

From Kanchanaburi, head northwest on Highway 323 toward Sai Yok and Thong Pha Phum. The road follows the general direction of the Khwae Noi River and passes several major attractions.

By train

The railway from Kanchanaburi continues west to Nam Tok, along surviving sections of the former Thailand–Burma Railway — the journey itself becomes part of the history.

By public transport

Buses and local transport connect Kanchanaburi with Sai Yok and destinations farther west. Reaching individual caves, waterfalls and river accommodation, however, often requires additional local transport.

One Day — Nature + History

Morning: Kanchanaburi → Sai Yok National Park → Sai Yok waterfall area → forest and river scenery.
Afternoon: Limestone cave experience → Khwae Noi River → continue toward the Hellfire Pass area.
Late afternoon: Hellfire Pass Interpretive Centre → memorial walking trail.
Evening: Return to Kanchanaburi or stay overnight in Sai Yok.

Two Days — The Better Way to Experience Sai Yok

Day 1 · River & Forest

Kanchanaburi → Sai Yok National Park → Sai Yok Yai → Khwae Noi River → cave exploration → riverside accommodation

Day 2 · History & Landscape

Morning river scenery → Sai Yok area → Hellfire Pass Interpretive Centre → historical railway landscape → return to Kanchanaburi

Two days let the park be experienced as a landscape rather than a checklist of attractions.

Travel Tips

Wear proper shoes

Caves, forest paths and railway trails can involve uneven surfaces, rocks, mud and slippery sections.

Carry water

Heat and humidity can be significant, particularly outside the cooler months.

Respect caves

Never touch cave formations unnecessarily. Do not disturb bats or other cave wildlife.

Don’t expect guaranteed wildlife

Sai Yok is a protected forest, not a wildlife park.

Check conditions first

Waterfalls, caves, trails and some facilities can be affected by rainfall, flooding, maintenance or seasonal safety restrictions.

Park vs district

Many attractions in Sai Yok District are not inside the national park boundary. Check each location rather than assuming everything labelled “Sai Yok” belongs to the park.

A Note on the Park Boundary

The current DNP park page continues to identify the original legal area as 312,500 rai / 500 km².

In 2025, however, the Department of National Parks announced a process to correct and revise the legal boundary after geographic-information-system checks found discrepancies between the original decree and the current mapped area. The proposed revised area was approximately 595,868 rai / 953.38 km², including the addition of Tha Sao Subdistrict and the removal of Bong Ti and Lum Sum from the administrative areas named in the original decree.

Four Landscapes, One Park

Sai Yok is best understood as a meeting point of four landscapes:

The River: The Khwae Noi gives the park its distinctive rhythm.
The Forest: Western Thailand’s forests provide the ecological foundation.
The Limestone: Caves and karst create a hidden world beneath the mountains.
The History: The railway landscape preserves memories of one of the region’s darkest periods.

A place where nature, geology, wildlife and history occupy the same landscape.

Frequently Asked Questions

Where is Sai Yok National Park?: Kanchanaburi Province, western Thailand — across Sai Yok and Thong Pha Phum districts along the Khwae Noi River, reaching the Myanmar border in the west.
What is Sai Yok famous for?: Sai Yok Yai Waterfall on the Khwae Noi River, Lawa and Dao Wadueng caves, Kitti’s hog-nosed bat, river scenery and Death Railway history.
Sai Yok Yai or Sai Yok Noi?: Sai Yok Yai is the park’s signature waterfall by the river. Sai Yok Noi (Khao Phang) is a smaller, easily reached roadside waterfall and a separate stop.
What is Kitti’s hog-nosed bat?: The bumblebee bat — the world’s smallest mammal by body mass at around 1.5–2 g, discovered in the Sai Yok area in 1973. Never disturb cave colonies.
How far is Hellfire Pass?: A short drive along Highway 323. The Interpretive Centre is open 09:00–16:00, with seasonal and holiday closures.
When should I visit?: November–February for comfort; May–October for green forest and stronger waterfalls; March–April is hot with lower water.
How do I get there?: Drive about 100 km northwest from Kanchanaburi on Highway 323, or take the railway west to Nam Tok and continue by local transport.
Can I stay overnight?: Yes — park houses and camping near headquarters and the Khwae Noi River, plus floating and riverside accommodation nearby.
How long should I spend?: One day for the highlights; two days to enjoy the river, caves and Hellfire Pass at a slower pace.

Essential Facts

Park: Sai Yok National Park · อุทยานแห่งชาติไทรโยค
Location: Sai Yok & Thong Pha Phum districts, Kanchanaburi, Thailand
Established: 27 October 1980 · National Park No. 19
Original gazetted area: 312,500 rai · approximately 500 km²
Highest mountain: Khao Khwae — approximately 1,327 m
Main river: Khwae Noi River
Signature waterfall: Sai Yok Yai
Other well-known waterfall: Sai Yok Noi / Khao Phang
Major caves: Lawa Cave · Dao Wadueng Cave
Signature wildlife: Kitti’s hog-nosed bat
Historical significance: Thailand–Burma Railway / World War II
Nearby heritage site: Hellfire Pass Interpretive Centre
Recommended stay: 1–2 days
Best for: Nature lovers, photographers, history travellers, cave explorers, river travellers & slow travel

Erawan National Park: Kanchanaburi’s famous seven-tier emerald waterfall.
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Thong Pha Phum National Park: Misty ridges and forest along the western border.
All Nature & Parks: Browse ThailandLover’s national park guides across the country.