Three Whale Rock (Hin Sam Wan)

Three Whale Rock (Hin Sam Wan) is a spectacular sandstone formation in Phu Singh Forest Park, Bueng Kan Province, northeastern Thailand. The site is named for its three massive, whale-shaped boulders that rest side-by-side on a high cliff, resembling a family of whales—father, mother, and calf—emerging from a “sea” of forest. From the rock’s summit, visitors can enjoy sweeping views of the Mekong River, the mountains of Laos, and the surrounding Phu Wua Wildlife Sanctuary.

The rocks sit on the Khorat Plateau in northeastern Thailand, a region famous for dinosaur-bearing sandstones, broad escarpments, and striking mesas. Three Whale Rock is composed of quartz-rich sandstone of the Phu Phan Formation (Khorat Group), deposited in river and floodplain environments during the Early Cretaceou. Over millions of years, weathering and erosion sculpted the resistant sandstone into smooth, elongated shapes that strikingly resemble whales.

Photo by: Thirawatana Phaisalratana

How Hin Sam Wan (Three Whale Rock) Formed

Three Whale Rock (Hin Sam Wan) is a quartz-rich sandstone unit deposited in fluvial (river, braided-stream, and floodplain) environments within the Khorat Basin during the Early Cretaceous (Barremian–Aptian, ~130–115 million years ago).

Sediment Deposition and Lithification: Ancient rivers spread thick beds of sand and mud across the Khorat Plateau. Over millions of years, burial pressure and silica-rich groundwater cemented these sediments into hard sandstone.

Tectonic Uplift: After deposition, the Khorat Plateau experienced gentle but repeated Cretaceous to Cenozoic uplift, which exposed the sandstone to surface weathering and erosion.

Differential Erosion: Softer surrounding rocks weathered away more rapidly than the durable quartz-rich sandstone, leaving resistant ridges and isolated blocks standing above the plateau.

Spheroidal Weathering: Tropical rainfall and daily temperature changes penetrated joints in the sandstone. Chemical dissolution of mineral cements and mechanical expansion caused outer layers to peel away, gradually rounding the blocks into smooth, elongated forms that resemble a family of whales.

Present Landscape: Today, massive sandstone slabs with curved tops and steep flanks rise above the forested plateau, a striking record of Early Cretaceous sedimentation and millions of years of tropical weathering.

Eroded crest of Three Whale Rock (Hin Sam Wan) sandstone.

Visiting Information

Season: Best from November to February (cool, dry season) for clear skies and comfortable temperatures.

Time of day: Sunrise offers soft light and fewer visitors; sunset provides dramatic colors but attracts larger crowds.

Access: Located in Phu Singh Forest Park, about 25 km southeast of Bueng Kan town. Visitors typically use park vehicles or pickups for the steep access road. Trails lead to viewing platforms on the “whale heads,” with panoramic views of the Mekong River and the mountains of Laos.

Safety: Facilities are basic, and cliff edges are unguarded—use caution.

Visitors atop Three Whale Rock (Hin Sam Wan).
Photo credit: Amikokung/IG

Facts About Three Whale Rock

Tourist Age Reference: Tourist sources often cite an age of 75 million years for the sandstone. However, this date likely refers to a period of tectonic uplift and exposure, not the rock's original deposition, which is significantly older.

Size: The largest of the three whale-shaped boulders is about 75 meters (246ft) long.

Iron Oxide Coatings: Reddish-brown surface colors come from thin coatings of iron oxide formed during chemical weathering.

Protected Area: Three Whale Rock lies within Phu Singh Forest Park, which conserves the fragile sandstone and promotes eco-tourism.

Fossil: While fossils are rare in the rock itself, nearby layers of the Khorat Plateau contain dinosaur footprints and plant fossils of similar age.

Local Legend: A Thai legend says three guardian whales once protected fishermen in the Mekong River; when harmed, their spirits remained as these massive rocks, symbolizing protection and good fortune.