The Cheow Lan Lake, nestled in the heart of Khao Sok National Park in Surat Thani province, is a 165 km² expanse of water bordered by limestone peaks. It is explored by longtail boat and stands as one of southern Thailand's most distinctive landscapes.

Why visit Cheow Lan Lake

The site brings together three rare elements on mainland Thailand: a moderately elevated artificial lake, an ancient humid tropical forest (one of Southeast Asia's oldest, estimated at over 160 million years old) and spectacular karst relief. Limestone cliffs rise directly from the green water, sometimes soaring over 300 metres high.

Unlike the nearby tourist islands, visitor numbers remain modest and access is exclusively by boat from the dam's landing. The most memorable experience is spending a night in a floating accommodation (rafthouse) moored along the shoreline, with neither connectivity nor roadside neighbours.

History of the lake and Ratchaprapha Dam

Cheow Lan Lake does not occur naturally. It was created in 1987 by the flooding of the Ratchaprapha Dam, built on the Pasaeng (Phra Saeng) river for hydroelectric and flood control purposes. The reservoir inundated an inhabited valley: villages, rice paddies and plantations were submerged, and residents relocated to the park's periphery.

This origin earned the lake the evocative nickname of Thailand's "Atlantis". Beneath the surface lie remnants of submerged hamlets, sometimes visible during the lowest water levels. The karst peaks visible today are the residual summits of an ancient massif, isolated by rising waters and shaped over millennia by erosion on limestone and granite rocks.

Since the 1990s, the zone has been integrated into national park management and economic activity rests primarily on regulated fishing and ecotourism.

What to see and do on the lake

Navigate by longtail boat

The motorised longtail boat remains the traditional mode of circulation and the sole means of accessing most of the lake's sites. Excursions depart from the dam landing and typically last from half a day to several days. The classic tour passes the most photographed rock formations, notably "Khao Sam Kloer", three aligned peaks nicknamed Thailand's "Guilin" in comparison to Chinese landscapes.

Sleep in floating accommodation

Several rafthouses are positioned directly on the lake, anchored in coves. The wooden or bamboo bungalows float on platforms and offer direct water access for swimming. Stays typically include boat transfers, meals and a guided excursion the following morning, the prime period for wildlife observation.

Hike and explore caves

Several trails depart from the coves and lead to karst caves, including Nam Talu cave (an aquatic route passing through the mountain) and Pakarang cave. These hikes are undertaken only with a local guide due to the risk of sudden flooding during the rainy season—a fatal accident led to Nam Talu's temporary closure in 2007.

Observe wildlife

Khao Sok National Park is home to 311 recorded bird species and emblematic fauna: white-handed gibbons, clouded leopards, wild elephants, gaurs, tapirs and sun bears. Mammals remain elusive and dawn boat excursions offer the best observation chances. Hornbill, kingfisher, fish eagle and great argus pheasant are among the birds regularly spotted along the shoreline.

Practical information

Park entry is charged (resident/non-resident rates differ) and is paid at the landing checkpoint. Boat excursions are organised on-site or via accommodations in the Khao Sok zone. Allow a minimum of half a day for an overview, or two days and one night for a more thorough visit. Bring water, sun protection, closed-toe shoes for hikes and a waterproof bag for camera gear. Mobile coverage is limited or non-existent on the lake.

When to visit

The dry season runs from January to April: clear skies, spectacular morning mists over the water, but high daytime temperatures and humidity. The rainy season, from May to December (peaking in September-October), brings frequent showers and milder temperatures, but vegetation is denser and waterfalls more active. Hikes may be suspended during heavy rain for safety reasons.

How to get there

The lake is accessible from the Ratchaprapha Dam landing, approximately 1 hour's drive from the Khao Sok accommodation zone.

• From Bangkok: overnight train to Phun Pin station (Surat Thani), then bus or minivan to Khao Sok (approximately 2 hours). Allow one night for rail travel. Direct bus from Bangkok takes about 6 hours.
• From Phuket: approximately 2 to 2.5 hours by minivan or private car.
• From Surat Thani: bus or minivan, approximately 2 hours.

Nearby attractions

• Khao Sok National Park: hiking trails through primary forest, around the visitor village.
• Krung Ching Waterfall: one of southern Thailand's finest waterfalls, in Khao Luang National Park.
• Ao Thalane: mangrove bay explorable by kayak, on the Krabi side.
• Wat Tham Suea: Tiger Cave temple, in Krabi.

To incorporate Cheow Lan Lake into a bespoke itinerary in southern Thailand, consult our Thailand trips.