Khao Sok National Park preserves 739 square kilometres of Thailand's oldest evergreen rainforest, a biosphere older than the Amazon by an estimated 160 million years.
Established in 1980, the park encompasses the Ratchaprapha Dam reservoir — locally known as Cheow Lan Lake — whose construction in 1982 submerged entire valleys and created a flooded landscape of limestone towers that rise 960 metres above the water. The forest canopy shelters wild elephants, sun bears, clouded leopards, and the Rafflesia kerrii, a parasitic flower whose metre-wide bloom appears between January and March.
The park's two distinct zones operate independently: the headquarters area in Khlong Sok village offers riverside trails and bamboo rafting along the Sok River, while the lake zone, 65 kilometres northwest, serves as the gateway to Cheow Lan's karst islands and submerged caves. Conservation fees apply per zone, per day. Most Khao Sok tour from Khao Lak itineraries target the headquarters zone for morning jungle treks and afternoon river activities, returning visitors by late afternoon. Multi-zone access requires separate entry permits.
The park's lowland dipterocarp forest transitions to hill evergreen above 400 metres, with trails ranging from paved interpretive loops to unmarked ridge routes that require a licensed guide. The Ton Kloi Waterfall trail, a five-kilometre round trip from headquarters, crosses wooden bridges over tributaries before reaching a three-tiered cascade that flows year-round. Monsoon rains from May through November render trails slick and obscure river crossings; dry-season months between December and April offer the clearest access, though temperatures exceed 35°C by midday.
Cheow Lan Lake exploration involves long-tail boat transfers to floating raft houses, kayak circuits around limestone outcrops, and hikes to viewpoints that reveal the reservoir's full 165-square-kilometre expanse. Diamond Cave, accessible only by boat and a steep ascent, contains stalactite chambers lit by natural fissures. The park's biodiversity — over 300 bird species, 48 mammal species, and an estimated 5 per cent of the world's vascular plants — draws ecologists and wildlife photographers who spend weeks cataloguing specimens in transects invisible to day visitors.
7 hr 30 min
