Cheio Laan Reservoir


Home to the largest hydroelectric power plant in southern Thailand, Chieo Laan Lake was formed at the founding of the Ratchaprapa Dam in 1985. The lake inundated once prime riverine forest habitat in Khao Sok National Park and is dotted with hundreds of little islands, remnants of hilltops which have since been isolated by the flooding of the valley.

The reservoir is the largest man-made lake in southern Thailand and provides electricity and water to tens of thousands of households throughout the region.

Chieo Laan is frequented by visitors all year round and most of the tourism is centered around the southwestern and eastern sectors of the lake. With that in mind, it is easy to see why most of the wildlife is found in the northwestern sector of the park near Khlong Saeng Wildlife Sanctuary.

The lake is home to hundreds of species of mammals, reptiles and birds. Many visitors have reported sighting large mammals such as Asian Elephant, Gaur, Bantang, Malayan Tapir, Asiatic Black Bear, Malayan Sun Bear and Sambar. Most of these animals are spotted from kayaks or longtail boats cruising along the shores of the lake in the early mornings.

The forest supports a limited number of leopards but the tigers have nearly all been wiped out. A captive release program has been initiated in an attempt to reintroduce the species into the area.

The lake plays an important role as a breeding station for many species of freshwater fish. Rajaprabha fishing pier is evidence of the bountiful harvest which locals reap from the vast lake. Visitors staying overnight at any of the floating lodges will notice the hundreds of Red tailed and Silver Foil Barbs in the water. Some of the lodges operate fishing tours deep into the forested streams of the national park, where angers wrestle with the infamous Giant Snakehead and gargantuan Siamese Carp. The lake is also home to the biggest freshwater monster in the world, the Mekong Giant Catfish, a fish which can weigh as much as a Grizzly Bear and reaches the length of a pickup truck. Local fisherman are often seen hauling these massive creatures from the lake near the fishing pier in the late mornings.

Far north of Khlong Saeng Wildlife Sanctuary are a number of outlying pools and tributaries, some of which are still relatively untouched by man. Past expeditions into these remote areas proved to be a logistical challenge as the forest is thick and impenetrable, forcing the researchers to rely on the narrow waterways to navigate their way into the jungle. Research trips conducted by the forestry department have confirmed that Khlong Saeng Wildlife Sanctuary is one of the most diverse and richest natural habitats left in the south, rivaling even that of Hala-Bala Wildlife Sanctuary or Bang Lang National Park. If there is any place in Thailand where a new resident species of plant, bird or other wildlife could be discovered, this could very well be it.

Since this lake is man-made and still relatively new (the dam was flooded in 1986) much of the fauna in the region is still adapting to the environment. Many of the larger mammals are only starting to emerge from their forest hideouts in recent years while a number of bird species such Storm’s Stork are still highly secretive and have only been recorded via camera traps from deep in the wildlife reserve.


Main Attractions: Helmeted Hornbill, Grey headed Fish Eagle, Bat Hawk, Buffy Fish Owl
Other Attractions: Bushy crested Hornbill, White crowned Hornbill, Great Hornbill, Lesser Fish Eagle, Great Argus, Stork billed Kingfisher
Extirpated: Storm’s Stork

Since the only mode of transportation around the reservoir is by longtail boat, traversing the lake is fairly costly and somewhat time-consuming. Likewise, due to the limited number of trails which emerge from the edges of the lake, most of the birding must be done by boat. Some people will find this method of birdwatching to be somewhat restricting as it limits the amount of species or family groups which can be seen, primarily species which are large and easy to spot from a distance.

Nevertheless, the species which are known to exist within the park and wildlife sanctuary are not to be balked at or written off as “boring”.

Let’s start out by describing the resident raptor species: Cheio Laan is a well-known stakeout for both Grey headed Fish Eagle and Lesser Fish Eagle, two locally endangered and highly sought-after species. Oriental Hobby is also found among the limestone karsts and the rare Bat Hawk has been spotted high in the sky in the early evenings as it makes its way to its favorite hunting grounds. Even the majestic White bellied Sea Eagle is a resident here, despite the fact that the lake is located almost 100 kilometers inland from the nearest beach! Osprey are commonly encountered and when startled will often put on a display which is thrilling to observe and will excite any avid nature lover or photographer.

The lake is also one of the best places in the south to find hornbill. The park is home to Great, Wreathed, Bushy crested, White crowned and Oriental Pied Hornbill. These birds are usually very conspicuous and easy to spot. The rarest and most coveted of all the species is the Helmeted Hornbill; its long, featherless neck and elongated central tail feathers are reminiscent of something out of a Jurassic Park movie.

Black Hornbill and Wrinkled Hornbill are rumored to be present as well, although so far  there have been no local records which would substantiate their existence. Black Hornbill has been reported from other parks in the same forest block so there is a valid argument that the species could exist here in very limited numbers.

With an abundance of water and fish one would naturally consider the lake to be the perfect habitat for kingfisher. Indeed, the lake is well stocked with these masterful predators. Chieo Laan is home to 10 of the 15 species found in Thailand. The open water is home to Stork billed Kingfisher and in the winter one can find Black capped and Common Kingfisher as well. Along the forest edges and up the narrow tributaries one can find Ruddy, Oriental Dwarf, Blue eared and Blue Banded Kingfishers and on occasion even the Collared Kingfisher, a predominantly coastal bird, has been found on the lake. Banded Kingfisher and Rufous collared Kingfisher, both forest-dwelling species, can been heard calling from deep within the foliage.

At night the lake comes alive with the calls of Buffy Fish Owl. Also present but more difficult to locate are other night birds such as Bay Owl, Sunda Scops Owl, Collared Scops Owl, Brown Hawk Owl, Barred Eagle Owl, Javan Frogmouth, Gould’s Frogmouth, Grey Nightjar and Large tailed Nightjar.

Birders who park their boats along the forest edges will be able to hear many species of birds calling from the dense understory such as Black capped Babbler, Chestnut winged Babbler, Crested Jay, Orange breasted Trogon and Emerald Dove. While it may be possible to lure some species out into the open with the use of playback, most of the skulking species (such as babblers) will still refuse to emerge from their hideouts.

The most legendary and  elusive of all birds on the lake has to be the mysterious Storm’s Stork. Discovered months before the dam was flooded, the bird was thought to have been extirpated from the region until it was photographed in one of the outlying tributaries less than a decade ago. Sadly, rangers report that there are only three birds left alive and it is likely to go extinct within the next few years.

Accommodations and Fees

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The national park operates a number of floating bungalows which can be rented via the park’s official website. These bungalows are built on bamboo rafts and are anchored near the shore. They are perfectly safe, even in the monsoon season and come with three square meals included in the daily price. The bungalows are very rudimentary, some consisting of nothing more than a bamboo hut on wooden logs with a thatched roof and a single window. Inside the bungalow one will find a mosquito net with a thin mattress, pillow and blanket. The lodge charges per head and most of the bungalows operated by the DNP costs 1000 baht a night per person.

Electricity is provided by a generator which is turned on at sunset and shuts off at around 11 PM.

[To reserve a DNP bungalow in Khao Sok National Park, click here]

Those who may be concerned about malaria should not be worried; there are no mosquitoes on the lake (thanks to the millions of bats) and the possibility of finding a snake or any other life-threatening creature aboard the floating bungalows is next to impossible.

There are also numerous floating lodges which are privately owned. The quality is a definite step above the DNP lodges and the prices seem to reflect that as well.

All visitors must pay an entry fee at the DNP ticket booth before boarding the boats at the pier. The park entry fee is 300 baht for foreigners.



The biggest expense birders will face are the boat fees; transport to and from a lodge can cost anywhere between 3500 – 5000 baht round trip, and those staying multiple days can expect to pay double that. Let me remind you: there are a very limited number of trails, none of which can be accessed from any lodge; therefore, any birding trips around the lake or visits to various viewpoints or waterfalls must be done by boat. An afternoon or evening trip out onto the lake can cost somewhere between 800 – 1200 baht per trip, depending on the distance and duration of the trip.

One point to bear in mind is that the boatmen charge per trip, not per customer, so it makes sense to travel as a party rather than individually.

By rule the same boatman who picked you up from the pier is required to remain with you (or your party) for entire duration of your stay so it’s good to get to know him beforehand and communicate your needs and desires to avoid being disappointed.

Directions to Chieo Laan Lake – Khlong Saeng Wildlife Sanctuary

To get a better idea of the surrounding area, please zoom out by pressing Ctrl on your keyboard and scrolling with your mouse.

The only way to get to Chieo Laan Lake is through Ratchaprapa Dam, the giant hydroelectric power plant operated by EGAT. Most locals associate the lake with the dam so when asking for directions, it is easier to refer to the site as Ratchaprapa Dam rather than Chieo Laan Lake.

Getting to Ratchaprapa dam is not too difficult and can be accessed via public transport if a private vehicle cannot be arranged beforehand.

If driving from Phuket, head towards Phang Nga town on Highway 4. (You can also head northwards toward the town of Takuapa and then go east by way of Khao Sok National Park but I wouldn’t recommend it as it is farther to drive and more time consuming.) Once at Phang Nga, continue on Highway 4 heading towards Krabi and Surat Thani. Turn left at the T-junction onto Highway 415 and follow the signs to Surat Thani. At the next junction, turn right onto Highway 401 and continue heading towards Surat Thani. About five kilometers down the road, the lane splits into a wide four-lane dual carriageway, a sign that you have entered Ta Khun Municipality. The entrance to Rajjaprabha Dam will be on the left, marked by a large sign hung over the intersection at the corner of Ta Khun temple. The dam is operated by the Electric Generating Authority of Thailand (EGAT). Wat Ta Khun will be on the left hand corner of the intersection.

If coming from Bangkok, head south on Highway 4 (Petchkasem Road) until you reach Punpin and see the turnoff for Surat Thani Municipality. At this intersection, the left turn will take you to Surat Thani while the right turn will head in the direction of Phuket, Phang Nga and Krabi via Highway 401. Take the left turn under the overpass heading towards Phuket. Follow the signs to Rajjaprabha Dam which are posted along the way. The dam should be approximately 30 kilometers from the turnoff at Panom.

Personal Opinion

Pros: Best location on the west coast for finding hornbills; very scenic and picturesque; no mosquitoes or biting insects on the lake; high chance of encountering large mammals; one of the last truly undisturbed wildlife sanctuaries left in southern Thailand.

Cons: No trail network; birding from a boat is somewhat restricting; not a site for those interested in twitching or racking up a long list of birds; travel around the lake somewhat time-consuming and rather costlynational park entrance fee overpriced.

Birders are not going to rack up a huge list but will be rewarded with fantastic sightings of quality birds without having to trek all over the jungle. Whether a person chooses to stay on the lake for a day or two and take a few trips out during the day or whether one decides to make a single day trip around the lake, the experience is well-worth the time and expense. Twitchers or those looking to boost their numbers will most likely find this option less appealing for them, unless they are after specific species such as the Grey Headed Fish Eagle or Helmeted Hornbill.

Birding from a boat will be appealing to birders who are not keen on trekking for long distances along leech-infested trails, those who may be bringing the family along on vacation or those battling old injuries and physically unable make it up a forest trail. This option will also be appealing to bird photographers who want to spend less time on their feet and more time behind the lens.

Those with an eye for landscapes will thrill at the scenic beauty of the lake.

This page was last updated in March, 2018.

Cheio Laan Lake in Photos