Steep hike No. 2 of 11 by flow
Khun Si Waterfall: Free Entry, 500 m Hike and Hidden Cave
Khun Si Waterfall on Koh Samui: free entry, a steep ~500 m walk through durian plantations, a cave behind the falls and the best months to go.
Khun Si this month October
- Flow
- Roaring
- Strong, Oct-Dec
- Swim
- Too strong
- next swim month: January
- Island rain
- 295 mm
- over 16 days
This waterfall
Khun Si
- Form
- Tiered
- Kind
- Steep hike
- Walk in
- 10-15 min
- Distance
- 0.5 km out and back
- Difficulty
- 3 out of 5
- Surface
- dirt
- Swim
- 5 months Jan, Feb, Mar, Aug, Sep
- Elevation
- 200 m at the pin
- Facilities
- cave viewpoint, bar
- Entry Fee
- Free (though parking at nearby bars may be 50 THB)
- Hike Duration
- 10 to 15 minutes
- Difficulty
- Moderate (due to steep, slippery terrain)
- Unique Feature
- A traversable cave located behind the main water curtain
The trail in: Khun Si Waterfall Trail Also reached by Grand Viewpoint Traverse Show on map
50 THB
At the gate
parking only
Overview
Khun Si Waterfall is one of Koh Samui’s most authentic and rugged nature spots. Located in the north-central mountains between Maenam and Bophut, it remains largely untouched by the mass tourism that defines the island’s southern falls. This is a place where you can hear the rustle of the jungle canopy and the distant calls of farmers, rather than the hum of tour buses.
Khun Si Waterfall is a short but steep jungle walk: about 500 m and roughly 40 m of descent, which is why most visitors allow 30-45 minutes for the round trip including the cave. For the trail-only details, see the Khun Si Waterfall Trail guide.
The waterfall is a tiered cascade that flows over dark, moss-covered granite. It is framed by incredibly dense vegetation, making it feel like a scene from a tropical adventure film.
The Durian Plantation Hike
The journey to the falls is as much a part of the experience as the destination. The trailhead is located on private land that has been used for durian and rambutan farming for generations.
- Agricultural Heart: As you hike down the narrow dirt path, you’ll walk directly under massive durian trees. Between May and August, you can see the heavy, spiked “King of Fruits” hanging from the branches.
- The Trail: The walk is only about 500 meters, but it is very steep. The ground is often composed of loose red clay which becomes exceptionally slick after any amount of rain.
- Respect the Farm: Remember that these are working plantations. Do not pick any fruit, and be mindful of the irrigation pipes and pulley systems used by the farmers to transport their harvest up the mountainside.
The Hidden Cave
The most famous feature of Khun Si Waterfall is the “secret” cave. Unlike many other waterfalls where the water hits a solid rock face, Khun Si has a significant overhang on its main tier.
- Accessing the Cave: You can carefully scramble across the boulders at the base of the falls to reach the area behind the water.
- The Experience: Standing behind the roaring curtain of water is an incredible sensory experience. The air is filled with a cool, misty spray, and the sound of the falls is amplified by the cave walls.
- Safety Tip: The rocks leading into the cave are notoriously slippery. Use your hands for balance and never attempt the crossing if the water flow is too heavy.
Khun Si Viewpoint
Just a few hundred meters from the waterfall’s parking area is the Khun Si Viewpoint. It is widely considered one of the best “free” views on the island.
- The Panorama: On a clear day, you can see the entire northern coast, from the curves of Maenam Beach to the Big Buddha in Bang Rak.
- Beyond Samui: You can clearly see the silhouette of Koh Phangan across the water, and on exceptionally clear days, even the distant islands of the Ang Thong Marine Park.
Mr. Dee Chilling Hill Bar
Located right at the entrance to the waterfall path, Mr. Dee Chilling Hill Bar (also known as 9 Dee Garden) is the perfect base camp for your Khun Si adventure.
- Hospitality: Mr. Dee is a local legend known for his friendly nature and his deep knowledge of the mountain trails.
- The Food: This is not just a tourist trap; the kitchen produces some of the most authentic and highly-rated Thai food in the mountains. Their Pad Thai is often cited as the best on the island.
- The Vibe: With hammocks, rustic wooden furniture, and a steady mountain breeze, it’s a great place to wait out a sudden rain shower or reward yourself with a cold drink after your hike.
Getting There
Khun Si is located in the hills inland from Bophut and Maenam.
- The Road: You access the falls via the “central mountain road” that connects the north and south of the island.
- Vehicle Choice: The road is paved but very narrow, steep, and often has cracks or debris. A 4x4 vehicle is ideal. If you are on a scooter, ensure it is at least 125cc and that you are an experienced mountain rider.
- Navigation: Search for “Mr. Dee Chilling Hill Bar” on Google Maps. The waterfall path starts just behind his garden. From the ring road (Route 4169), follow the signs toward Wat Thale temple and then up the mountain road.
| From | Distance (approx.) | Drive time |
|---|---|---|
| Chaweng or Lamai | 10-15 km | 20-40 min |
| Bophut or Maenam | short climb inland | 10-15 min |
Distances are approximate and depend on traffic and the route you choose. Scooters and songthaews are the usual options; a taxi driver may need the bar’s name rather than the waterfall’s.
Opening hours and fees differ by source. Some listings give 6:00 to 18:00 daily (see the Tripadvisor page) and a 50 THB (~1.50 USD) parking or garden fee, while others say entry is free. Plan to arrive in daylight and confirm locally.
What to Expect at the Falls
The path is short but rough, so the first view of the falls comes after a steep scramble on red clay rather than a flat stroll. Expect a tiered cascade over dark granite, a natural pool at the base that is deep enough for a dip, and boulders around the water that are slippery even in dry weather.
- Crowds: Visitors report having the place almost to themselves early in the day, so go in the morning if you want quiet.
- Swimming: Fine in the base pool when the flow is moderate. Skip it when the water is high and brown after heavy rain.
- Time needed: 30-45 minutes at the falls and cave, plus time at the viewpoint and the bar.
- After the hike: The viewpoint and Chilling Hill Bar are a few minutes back up, so you can pair the falls with a meal and the coastline views.
Best Time to Visit
Khun Si is highly dependent on rainfall. In the peak dry season, the “roaring curtain” can become a mere drip.
| Season | Water Level | Vibe |
|---|---|---|
| Oct - Dec | Very High | Dramatic and powerful; cave may be hard to access due to spray. |
| Jan - Mar | Moderate | Ideal for swimming and exploring the cave. |
| Apr - June | Low | Very quiet; great for the viewpoint and Chilling Hill Bar. |
| July - Sep | Rising | Refreshing and lush; durian season is in full swing. |
Island rain, mm, above the line This fall's flow below it: strong, good, low; dotted is dry Swim month
January The swim months: water to swim in
- Flow: Rushing
- Swim OK
- 125 mm over 8 days
- Island crowds high
February The swim months: water to swim in
- Flow: Rushing
- Swim OK
- 65 mm over 4 days
- Island crowds high
March The swim months: water to swim in
- Flow: Rushing
- Swim OK
- 115 mm over 5 days
- Island crowds moderate
April A thin line of water, wade in the pools
- Flow: Trickling
- Too low
- 85 mm over 6 days
- Island crowds moderate
May A thin line of water, wade in the pools
- Flow: Trickling
- Too low
- 130 mm over 11 days
- Island crowds low
June A thin line of water, wade in the pools
- Flow: Trickling
- Too low
- 135 mm over 10 days
- Island crowds low
July A thin line of water, wade in the pools
- Flow: Trickling
- Too low
- 115 mm over 11 days
- Island crowds moderate
August The swim months: water to swim in
- Flow: Rushing
- Swim OK
- 100 mm over 10 days
- Island crowds moderate
September The swim months: water to swim in
- Flow: Rushing
- Swim OK
- 120 mm over 11 days
- Island crowds low
October Most dramatic, admire it from the rocks
- Flow: Roaring
- Too strong
- 295 mm over 16 days
- Island crowds low
November Most dramatic, admire it from the rocks
- Flow: Roaring
- Too strong
- 445 mm over 16 days
- Island crowds low
December Most dramatic, admire it from the rocks
- Flow: Roaring
- Too strong
- 265 mm over 12 days
- Island crowds high
Khun Si and three other falls
Each card shows a fall's year, with this month marked, so you can see which one fits your day.
Khun Si Waterfall vs the Viewpoint: Which Do You Need?
Do both: the viewpoint is only a few hundred metres from the parking area, whereas the waterfall needs the steep 500 m path. If rain has made the clay slick or you have small children, the Khun Si Viewpoint and a drink at the bar still give you the best part of this corner of the island.
Practical Tips
- Footwear: Do not attempt this hike in flip-flops. Sturdy sneakers or specialized hiking sandals are a must.
- Mosquitoes: Being in a fruit plantation near standing water means mosquitoes are everywhere. Bring high-DEET repellent.
- Connectivity: Cell service can be spotty in the deep ravine. Download your offline maps before heading into the mountains.
- Timing: Leave the area by 5:00 PM. The mountain roads are not illuminated, and navigating the steep turns in the dark is dangerous.
FAQ
How long is the walk to Khun Si Waterfall? About 500 m each way, steep and on loose red clay. Allow 10-15 minutes down and a little longer back up. Mapping apps such as AllTrails list a similar distance with roughly 40 m of elevation change.
Is Khun Si Waterfall worth visiting? Yes, if you like a short, rough walk through durian farms to a free waterfall with a cave behind it, and you go between October and March when there is enough water. In the dry months the flow can shrink to a trickle, and the viewpoint becomes the main reason to come.
Is there an entry fee for Khun Si Waterfall? Technically no, but you usually have to pay 50 THB for parking or access through the private gardens. Buying a drink at Chilling Hill Bar often covers your parking.
Can I swim here? Yes, there is a natural pool at the base of the main fall. It is deep enough for a refreshing dip but not for diving.
How do I find the cave? Walk to the base of the waterfall. On the right-hand side, there is a scramble path that leads behind the water curtain. Be extremely careful.
Is it safe for children? The path is very steep and can be dangerous for small children. We recommend this spot for adults and older children who are confident on uneven terrain.
Are there durians I can buy? Often, the local farmers or Mr. Dee will have fresh fruit for sale depending on the season. It is a great place to try authentic Samui durian!
Before you go
Where this water comes from
The water comes down from 432 m of hillside
Khun Si sits 3 of 11 by height. Rain on the slopes above reaches the pool before the sky over it turns: watch the hills, not the pool.
Rule one: Rising flow
If it rains upstream, get out of the water
Rain upstream can lift a fall's flow within the hour, well before it starts raining where you're standing. Watch for water that turns brown, rises or gets louder, and take the way down slowly.
-
Wet rock
Granite turns slippery within seconds of getting wet, shaded patches included. Move slowly near any ledge.
-
Never dive
Pool depth shifts with the season and the rock underneath is often out of sight. Wade in, don't jump.
-
Wear real shoes
Flip-flops slide on wet stone. Closed shoes or grippy sandals make every one of these walks safer.
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Carry it out
None of these trails have bins along the way. Whatever you bring in, fruit peel included, leaves with you too.
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Some gates charge
A few of these falls sit on private land with a gate fee. That's normal here, not a tourist markup.
Nearby Places
Bearings from the pool
What else is close
Beaches
- Bophut Koh Samui 4.7 km NNE, 20°
- Chaweng Noi Beach 4.9 km ESE, 110°
Temples
- Wat Teepangkorn, Koh Samui 2.4 km SSW, 202°
- Wat Sawang Arom 3.6 km ENE, 73°
Hikes
- Grand Viewpoint Traverse 0.2 km ENE, 69°
- Khun Si Waterfall Trail 0.2 km ENE, 69°
Waterfalls
- Tan Rua Waterfall (Secret Falls) 2.8 km WNW, 302°
- Tarnim Magic Garden 4.8 km SSW, 206°