Khao Sok National Park (Thai: เขาสก, pronounced [kʰǎw sòk]) is located in Surat Thani Province, Thailand. The park covers an area of 461,712 rai, which is about 739 square kilometers (285 square miles). It includes Cheow Lan Lake, a body of water measuring 165 kilometers (64 square miles) in size, which is formed by the Ratchaprapha Dam. This park is the largest area of untouched forest in southern Thailand and represents a part of an ancient rainforest that is older and more varied than the Amazon rainforest.

Geography

Sandstone and mudstone rocks rise about 300–600 meters (984–1,969 feet) above sea level. A limestone mountain range crosses the park from north to south, reaching a highest point of 950 meters (3,117 feet). This mountain range receives monsoon rain from both the Gulf of Thailand and the Andaman Sea, making it one of Thailand's wettest regions with an annual rainfall of 3,500 mm (137.8 in). Heavy rainfall and falling leaves caused erosion of the limestone rocks, forming the notable karst formations seen today.

Flora

Bamboo holds topsoil strongly, helping to stop soil from washing away on hillsides and riverbanks. With more than 1,500 species, bamboo is the oldest grass in the world, having existed for about 60 million years. Liana trees grow quickly by wrapping around vertical or horizontal supports like takian or "rain trees." Because of this, cutting a tree in the jungle can be dangerous, as it may pull connected liana vines, causing more damage. Buttress roots are thick, wide roots found on some trees that grow above the upper canopy. Scientists believe these roots either help trees stay stable during storms or spread out to absorb more nutrients.

Many types of wild fruit grow in the national park and provide food for animals. These include wild jackfruit, mangosteen, durian, rambutan, jujube, pomelo, and wild bananas. Wild pepper and ginger are also commonly found. Khao Sok National Park is famous for the bua phut (Rafflesia kerrii) flower.

Wildlife

The park is believed to have more than five percent of all species found worldwide. Wild mammals living there include the Malayan tapir, Asian elephant, sambar deer, bear, gaur, banteng, serow, wild boar, pig-tailed macaque, langur, white-handed gibbon, squirrel, muntjak, mouse deer, and barking deer.

Many websites say that tigers live in Khao Sok National Park. Historical records show tigers were there several decades ago, but there is no evidence from camera traps to prove they still live in Khao Sok or nearby forests.

In 2001, scientists discovered the world’s first known amphibious centipede, Scolopendra cataracta, near a stream bank close to the national park. This centipede can live both in water and on land.

The area near the Ratchaprapha Dam in Khao Sok is the last natural home in Thailand for the Asian arowana, a rare fish that has existed for a long time and is in danger of disappearing.

Climate

The wet season occurs from late April to December. The temperature stays between 22 and 36 degrees Celsius (72 to 97 degrees Fahrenheit) throughout the year. High humidity and warm temperatures create perfect conditions for a diverse ecosystem in this tropical rainforest.

Natural history

This area is estimated to be over 160 million years old. It was formed by tectonic movements, changes in climate, erosion, and the buildup of sediments. About 300 million years ago, shallow water and warm temperatures in this area helped form a very large coral reef. This reef was estimated to be five times larger than the Great Barrier Reef in Australia. It once stretched from China to Borneo. The collision of the Indian and Eurasian plates between 0 and 66 million years ago formed the Himalayas. The area that is now Thailand moved significantly near the continental divide. This movement pushed limestone rocks upward, creating the dramatic limestone "karsts" that the region is known for today. Finally, melting ice created a landscape with many rivers and dozens of waterfalls around the national park.

Human history

The first people to move to Thailand came from Borneo during the Ice Age, about 37,000 years ago.

The earliest records of people living in Khao Sok date back to the 1800s, during the time King Rama II ruled. During the Burmese-Siamese War (1809–1812), the Burmese army attacked the western part of the area, causing the people there to flee inland. They found the region very attractive because of its natural beauty, rich wildlife, and fertile soil. As word spread about this place, more people moved there to live.

In 1944, the people in this area suffered from a serious illness. Many villagers died, and the survivors left to live in Takua Pa nearby.

In 1961, a road called Route 401 was built, connecting Phun Pin in Surat Thani Province to Takua Pa in Phang Nga Province. At the start of the 21st century, efforts began to widen Route 401 into a four-lane highway.

During the 1970s, Thai student activists and communist groups used the caves in Khao Sok as bases. They lived in the rainforest and protected the area from the Thai army, loggers, miners, and hunters for seven years.

Khao Sok became a national park in 1980. The government and the Electricity Generating Authority of Thailand (EGAT) were interested in the area because it contains the largest watershed in southern Thailand.

Two years later, EGAT finished building the Ratchaprapha Dam, which is 94 meters (308 feet) high. The dam blocked the Klong Saeng River, a branch of the Phum Duang River, and created a lake covering 165 square kilometers (64 square miles) inside the park. The dam supplies electricity to southern Thailand, and the lake became a popular tourist destination for both Thais and foreigners. To save animals from being flooded, some species were relocated before the lake filled over three years. However, a study in 1995 found that about 52 types of fish in the river could not survive in the still water of the lake.

Activities

Khao Sok National Park offers many outdoor activities for visitors.

Trekking: During the day, tourists can enter the West Entrance to hike on maintained trails. Visitors often see monkeys, tropical birds, and insects. Wild elephants, serow, and Malayan sun bears may also be spotted. The rare Rafflesia Kerrii Meijer flower grows in the area. Those interested in trekking can hire a local guide. Guides are needed for nighttime tours. Overnight stays in the rainforest are allowed with proper arrangements.

Canoeing and Bamboo Rafting: The Sok River offers scenic views along its banks. Local guides are available for canoeing and bamboo rafting trips.

Boat Tours: Cheow Lan Lake is the most popular attraction, with its beautiful limestone cliffs and turquoise water. Several caves, including Diamond Cave, Khang Cow Cave, and Nam Talu Cave, are located across the lake. Nam Talu Cave is approximately 12 kilometers (7.5 miles) from the park's headquarters. Tour guides accompany visitors from the waterfall to the lake.

Gallery

• The Khao Sok tropical rainforest.
• Views of Cheow Lan Lake during early morning hours.
• Views of Cheow Lan Lake during early morning hours.
• Karst formations on Cheow Lan Lake.
• Trees growing up from Cheow Lan Lake.