A rainforest where a lake of 185 square kilometres was dammed in 1987, and where limestone cliffs have risen from the water ever since, as if from a fjord.
The lake Khao Sok is famous for is not a natural wonder but a power station reservoir, and that is exactly what explains its shape.
On 9 February 1982 the state electricity authority EGAT began building a dam in the north-east of today's park. It was finished in September 1987, and on 30 September 1987 King Bhumibol, accompanied by Princess Maha Chakri Sirindhorn, inaugurated it. The operator calls it the second multi-purpose dam in the south; it used to be called Cheow Lan Dam, and the name lives on in the lake.
What formed behind the 94-metre (308 ft) rockfill is, according to the operator, a lake of 185 square kilometres holding 5.6 billion cubic metres. Many guidebooks give 165 square kilometres; we follow the operator's figure. The water flooded a valley in the limestone mountains. Since then the karst summits have stood out as islands, and the valleys between them are arms of the lake, hence the fjord-like shape that no natural lake in Thailand has.
Beneath the water lies the former valley floor with its forest. In shallow places dead trunks still stand in the lake today, remains of the forest that drowned when the reservoir filled. When you are out on a boat, you are travelling over a sunken landscape.
The power station works with three turbines of 80 megawatts each and generates around 554 million kilowatt hours a year. For visitors this means the lake is an operating reservoir, not a natural body of water, and its level follows the power station's needs.
Visiting Khao Sok National Park: two entrances, 30 km (18.6 mi) apart
01
738.74 square kilometres
That is the size of the park according to the tourism authority, including the area north of the Rajjaprabha Dam. The ASEAN Centre for Biodiversity gives 660.65 square kilometres. Both figures come from official bodies; we give both.
Khao Sok was declared in 1980. The tourism authority describes it as the centre of the largest rainforest area in all of southern Thailand and as the source of the Tapi River.
The headquarters, with trails along the Sok and its waterfalls, is in the village of Khlong Sok. The reservoir begins at the Rajjaprabha Dam, around 30 kilometres (18.6 mi) east as the crow flies. If you want to see both, plan two days or a transfer.
In 2021 Khao Sok became the 50th protected area to join the ASEAN Heritage Parks, the seventh in Thailand. The title is not UNESCO World Heritage but the regional award of the South-East Asian states.
34 Mu 6, Khlong Sok, Phanom, Surat Thani 84250. Telephone +66 77 395 139 and +66 77 395 154. The tourism authority gives khaosoknpks@hotmail.com as the email address.
„Beneath this boat lies a forest. The mountains that are islands here were summits until 1987.“
Khao Sok National Park · Longtail boat on the Rajjaprabha Dam reservoir
Cheow Lan Lake tour & hikes: by boat on the lake, on foot to the waterfalls
Longtail boat on Cheow Lan Lake
Boats leave from the pier at the dam onto the lake, past limestone cliffs that, in the tourism authority's description, rise from mirror-like water. The best-known sight is Three Rocks, three rock pinnacles close together.
Two caves on the lake shore, both reachable only by boat. Diamond Cave is a stop on many boat tours, with a short path from the landing; Coral Cave is in the north of the lake.
From the headquarters the main trail follows the river to Wing Hin, then past the Bang Hua Rad ranger post to Ton Kloi Waterfall. The tourism authority names Mae Yai and Sip Et Chan waterfalls as the easiest to reach.
The ASEAN Centre for Biodiversity counts 296 bird species in the park. The tourism authority explicitly names the blue-winged pitta and the Malayan banded pitta, both ground birds of the rainforest.
Khao Sok: private longtail boat on Cheow Lan Lake, early or in the afternoon
Four to six hours in your own boat with a local boatman on the reservoir, past the limestone cliffs, with a swimming stop and Diamond Cave. Departure either at six for sunrise or at half past two for sunset.
4 to 6 hours
private boat
Departure 6:00 or 14:30
Life jacket and water
Departure Meeting point at the steps in front of the information building near the Cheow Lan pier, or hotel pick-up.
Explicitly not included: the national park fee, which the operator itself gives as 300 baht per adult and 150 baht per child, the pier fee of 40 baht per person, 40 baht parking if you come by car, and lunch. We point out a contradiction with the official bodies: the description calls the park the oldest rainforest in the world, which none of the authorities we checked claims. Not suitable for people with reduced mobility. Cancellation up to 24 hours in advance.
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Khaolak Planner · GetYourGuide
From Khao Lak: half-day rainforest hike from the Khao Sok headquarters
Small group of no more than seven guests: registration at the national park headquarters, then around five to six kilometres (3.1–3.7 mi) there and back through the rainforest along a stream to a swimming spot. On the way back to Khao Lak, a stop at the viewpoint over the rainforest.
5–5.5 hours
5–6 km (3.1–3.7 mi)
Park entry included
English
Departure Hotel pick-up in Khao Lak, morning or afternoon.
Included are guide, transfer, entry, limited insurance and a raincoat; tips are not. The product URL speaks of a night tour, while the title and description describe a day hike leaving in the morning or afternoon. The page gives the minimum age once as 7 years and elsewhere as "not suitable for children under 6"; check before booking. Runs in all weather; free cancellation up to 24 hours in advance.
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Khaosok Eco Adventure · Hike · 4 hours
Khao Sok: half-day hike to the Wing Hin and Bang Hua Rad waterfalls, with pick-up in Khao Sok village
Four hours with a guide on the main trail through the park's rainforest, looking out for monkeys, gibbons and insects. The goal is the Wing Hin and Bang Hua Rad waterfalls on the Sok, with time for a swim. Hotel pick-up and return in the Khao Sok area.
4 hours
Pick-up in Khao Sok
Park entry included
English
Departure Hotel pick-up in the Khao Sok area; the page gives no separate meeting point.
Included are all national park entrance fees, pick-up and return in the Khao Sok area, an English-speaking guide, drinking water and travel insurance. Pick-up in Khao Lak is possible but not included and costs extra. Bring swimwear, a towel, hiking shoes, sunscreen and insect repellent; not suitable for children under 7 years or pregnant women. We point out a contradiction: the title speaks of a private tour, while the description offers shared and private groups. Free cancellation up to 24 hours in advance.
Cheow Lan Lake: two days with a night in a floating bungalow
Two days on the reservoir: a night in a superior floating bungalow with private bathroom and air conditioning, longtail boat to the tour stops, jungle hike, early-morning wildlife watching and kayaking on the lake.
2 days
Floating bungalow
Meals included
English or Thai
Departure The provider's office, according to the page the last one on the right before the river; getting there is not included.
Included are accommodation, boat trips, all meals and an English-speaking guide; not included are getting to the office and alcoholic and non-alcoholic drinks. The page does not mention park entry. Bring your passport; not suitable for people with reduced mobility or prone to seasickness. Free cancellation up to 24 hours in advance.
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Khaosok Eco Adventure · Evening · Night safari
Khao Sok: night safari on foot in the national park, with pick-up in Khao Sok village
After sunset, two hours on foot with a guide through the park's rainforest, looking for insects, reptiles and mammals that only become active after dark. Hotel pick-up and return in the Khao Sok area.
2.5 hours
Pick-up in Khao Sok
National park fee included
English
Departure Hotel pick-up in the Khao Sok area; the page gives no separate meeting point.
Included are pick-up and return in the Khao Sok area, guide, drinking water and the national park fee. Pick-up in Khao Lak is possible but not included and costs extra. Bring insect repellent and a torch; not suitable for children under 6 years. The page does not say which trail the group walks; the included national park fee and the description place the walk inside the park. We point out a contradiction: the title speaks of a private tour, while the description offers private and shared groups. Free cancellation up to 24 hours in advance.
Ad · we may earn a commission if you book through this partner link. Offer details checked 2 Oct 2026. See official ticket information.
Nature: rainforest, limestone and a flooded valley floor
65 per cent rainforest, 25 per cent reservoir
The ASEAN Centre for Biodiversity divides the park into moist evergreen forest on around 65 per cent of the area, the reservoir on around 25 per cent and limestone karst on around nine per cent.
95 mammal species, 96 reptile species, 46 amphibian species, 296 bird species and 118 fish species: that is the tally of the ASEAN Centre for Biodiversity.
The centre lists the sedge Khaosokia caricoides, the balsam Impatiens sirindhorniae and Rafflesia kerrii as endemic. The tourism authority adds the white-backed palm and Maxburretia furtadoana.
This claim appears in many tour descriptions, including one of the operators linked here. None of the official bodies we checked makes it. The tourism authority speaks of the largest rainforest area in southern Thailand, and that is documented.
85 seconds from the Thai national park authority's channel about the Rafflesia in Khao Sok, the flower that grows only here and in the neighbouring park. In Thai; the pictures speak for themselves.
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01Best time to visit: rain is part of it, and so are closures
Six months of rainy season, and the park authority closes trails without notice in heavy rain.
Six months of rain, three cool, three hot
The tourism authority sums up the country's climate like this: six months of rainy season, three months of dry, cooler air in winter and three months of heat. Average temperatures range between 18 and 38 °C (64 and 100 °F).
On 25 September 2026 the park authority announced, on a single day, the temporary closure of Khao Yai after landslides, and of Nam Tok Chet Sao Noi and Khao Chamao-Khao Wong, each from 25 to 27 September, because of heavy rain. Khao Sok was not affected, but this is exactly how closures happen.
The tourism authority gives this period for the flowering of Rafflesia kerrii. Each flower takes nine months to reach full size and then blooms for only four to five days.
Best months by the climate data: January and February. Average daytime highs of 27 to 29 °C, lows of around 21 °C, 30 to 93 mm of precipitation a month. The wettest month is September (352 mm), the driest February (30 mm).
20°25°30°35°
Jan2721
Feb2921
Mar3022
Apr3224
May2924
Jun2824
Jul2723
Aug2723
Sep2723
Oct2823
Nov2823
Dec2722
High °CLow °C
Daily highDaily lowPrecipitation
All monthly values as a table
Monthly averages 2001–2020, NASA POWER model
Month
High °C
Low °C
Precipitation mm
January
27.4
21.3
93
February
28.6
21.1
30
March
30.5
22.4
114
April
31.5
23.8
129
May
29.1
24.0
274
June
27.8
23.6
291
July
27.4
23.3
290
August
27.4
23.2
301
September
27.4
23.0
352
October
27.6
23.0
330
November
27.7
22.7
248
December
27.2
21.8
154
Year
2,606
Modelled values, not a weather station: NASA POWER (MERRA-2) for a grid cell of about 55 × 70 km around the map point Khao Sok headquarters (8.92° N, 98.53° E), with an average cell elevation of about 220 m. Averages for 2001–2020. Higher ground and valleys can differ markedly.
The boat pier is at the Rajjaprabha Dam, around 30 kilometres (18.6 mi) east of the headquarters as the crow flies. If you want to see forest and lake in one day, you need a transfer; day tours to the lake usually include one.
The dam is operated by the state electricity authority EGAT. With three turbines of 80 megawatts each, the power station has a total output of 240 megawatts and generates around 554 million kilowatt hours a year.
On top of park entry, according to the boat operators, there is a pier fee of 40 baht per person at the lake and a parking fee if you come by car. Payment is usually in cash.
Baan Khaosok Tour & Travel · Day trip to the lake · 7 hours
Khao Sok: day trip from the headquarters to the reservoir, park entry included
Seven hours with transfer to the dam, a longtail boat trip across the lake, a short jungle path to Diamond Cave and a Thai lunch. Guided in Thai and English.
Departure Pick-up in the Khao Sok area.
The counterpart to the private boat trip: here "national park entrance" is explicitly on the list of inclusions, as are the transfer to the dam, lunch and accident insurance. Only personal expenses and tips are excluded. This solves the park's real access problem, the roughly 30 kilometres (18.6 mi) as the crow flies between the village of Khlong Sok and the lake. The figure of over a hundred islands over 60 kilometres (37 mi) comes from the operator; we could not confirm it officially. Cancellation up to 24 hours in advance.
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03Tickets & entrance fees: 300 baht or 200? Two authorities, two prices
Under "Official Information" for Khao Sok, the Tourism Authority of Thailand (TAT) lists 300 baht for foreign adults and 150 baht for foreign children.
The fee regulation of the park authority DNP, published in the Royal Gazette on 9 December 2021 and in force since 7 June 2022, divides all national parks into four groups. Khao Sok is in group 2: foreign adults 200 baht, children 100 baht, Thais 40 and 20 baht.
We have not found a later change for Khao Sok from the authority. But the TAT page gives 300 baht, and a boat operator with almost a thousand reviews explicitly excludes "300 baht per adult" as the park fee. If you plan with 200 baht, you may end up at the entrance with too little cash.
In September 2022 the park authority set higher foreigner rates for particularly busy destinations: Khao Yai, Phi Phi and Lanta 400 baht, Samet and Ang Thong 300 baht. Khao Sok is not on that list.
Under the regulation a car costs 30 baht, a six-wheeled vehicle 100 baht, up to ten wheels 200 baht, a motorbike 20 baht. At the lake pier, according to the boat operators, a pier fee of 40 baht per person is added.
Free entry applies to children under three, monks and clergy of other religions living in Thailand, and people with disabilities. A child is anyone aged between 3 and 14 or no taller than 140 centimetres. A foreigner is anyone without Thai nationality.
According to the park authority's notice, the per-person fee covers a stay with overnight stays of up to five days per visit. So keep your ticket: unlike in Namibia, each day is not charged separately.
04Where to stay: at the headquarters or in floating bungalows on the lake
The park authority's accommodation is booked through its own portal; on the lake you stay in raft houses.
Park authority accommodation
Rooms, campsites and huts in Thai national parks are booked through the park authority's booking portal, after registering. When we checked on 25 September 2026, the portal could not be reached from Germany.
Overnight stays in floating raft houses on the lake are sold as multi-day packages with boat and meals. A checked offer with a night in a floating bungalow is listed with the tours.
The risks are unspectacular, but they are the ones that make visits fail.
Rivers rise quickly in heavy rain
The park authority closes trails and entire parks when heavy rain is expected to cause flooding. If you come in the rainy season, check the authority's current announcements and follow the rangers' instructions.
Fees are collected in cash at the entrance, and the two authorities give different amounts. With 300 baht per adult plus 40 baht for the pier and a parking fee, you are on the safe side.
According to the ASEAN Centre for Biodiversity, Asian elephant, sun bear and clouded leopard live in the park; 95 species are on the IUCN Red List, six of them critically endangered.
The flower grows as a parasite whose host runs through the forest floor. Every step off the trail can damage it. Only look for flowers on marked trails and with a guide; that is why we do not give any locations.
06Frequently asked questions: Khao Sok National Park
How much is the entrance fee for Khao Sok National Park?
Budget 300 baht per adult and 150 baht per child, in cash at the entrance. That is what the Tourism Authority of Thailand (TAT) gives, and local boat operators also exclude it as the park fee. The park authority's 2022 fee regulation, however, puts Khao Sok in group 2 at 200 and 100 baht. We have not found a later change, but we still recommend the higher amount.
At the Cheow Lan Lake pier operators charge a pier fee of 40 baht per person, plus a parking fee if you come by car. Whether park entry is already included depends on the tour: of the offers linked here, one includes it and the other does not.
How far is Cheow Lan Lake from Khao Sok headquarters?
Around 30 kilometres (18.6 mi) as the crow flies. The headquarters with the forest trails is in the village of Khlong Sok, the boat pier at the Rajjaprabha Dam further east. If you want both in one day, you need a transfer; day tours to the lake usually include one.
Between November and April, according to the tourism authority. A single flower takes nine months to reach full size and then blooms for only four to five days; exactly when cannot be planned. It grows only in Khao Sok and in neighbouring Khlong Phanom National Park.
Many operators say so, but none of the official bodies we checked. What is documented: the tourism authority calls Khao Sok the centre of the largest rainforest area in southern Thailand, and the ASEAN Centre for Biodiversity lists 95 Red List species.
738.74 square kilometres according to the tourism authority, including the area north of the dam. The ASEAN Centre for Biodiversity gives 660.65 square kilometres. The reservoir alone measures 185 square kilometres according to the operator.
Yes. In the rainy season the park authority closes trails and entire parks without notice in heavy rain; on 25 September 2026 this affected Khao Yai, Nam Tok Chet Sao Noi and Khao Chamao-Khao Wong. Check the authority's announcements before your visit.
How many days do you need in Khao Sok National Park?
Two, if you want to see both the forest and the lake. The headquarters with its trails and waterfalls in Khlong Sok and the reservoir at the Rajjaprabha Dam are around 30 kilometres (18.6 mi) apart as the crow flies. For both in one day you need a transfer.
Through one of its two sides. On the forest side you pay the entrance fee in cash at the checkpoint near the headquarters in Khlong Sok, where the trails start. The lake side is reached from the boat pier at the Rajjaprabha Dam.
Yes. Overnight stays in floating bungalows (raft houses) on Cheow Lan Lake are sold as multi-day packages with boat trips and meals, for example as a two-day tour with a night on the lake.
Park authority DNP, Tourism Authority of Thailand, dam operator EGAT and the ASEAN Centre for Biodiversity. Where they contradict each other, the text says so.
Researched 25 Sep 2026. Not a live status. Dates apply only to the year stated. A successful automatic fetch is not an editorial confirmation; outdated automatic values are hidden and replaced by the source link.
