Rio Celeste’s sky-blue river in the forests of Upala
Published on 08/21/2026 at 15:31 | Editorial responsibility: Rafael Müller, Editor-in-Chief AD HOC NEWS
In the northern forests of Costa Rica, Rio Celeste in Tenorio Volcano National Park turns an ordinary green landscape into an improbable scene of sky-blue water. North of the volcanic plains of Guanacaste and within reach of the small towns between Bijagua and Upala, this short stretch of river concentrates geology, rainforest and colour into a compact walk.
A sky-blue river shaped by a volcano
Rio Celeste flows through Tenorio Volcano National Park, a protected area in the country’s northern lowlands that forms part of the Arenal Tempisque Conservation Area.Tenorio Volcano National Park The park lies in Guanacaste and Alajuela provinces and wraps around the flanks of Tenorio Volcano, whose slopes carry lowland and premontane rainforest and a network of small rivers.Guanacaste Province, northern Costa Rica
One of those rivers is Rio Celeste, whose name points directly to its colour: a saturated turquoise that stands out strongly against dark trunks, wet stones and dense foliage. For much of its length inside the park the river runs close to the main trail, so the unusual colour is not a distant spectacle but a constant presence beside the path.
Where clear streams turn blue at Los Teñideros
The most striking single feature of Rio Celeste is that the river does not spring from the ground already blue. Upstream, two clear streams, the Buenavista River and Sour Creek (Quebrada Agria), run through the forest with the ordinary appearance of mountain water.Buenavista River and Sour Creek At a confluence known locally as Los Teñideros, they meet, and a short distance beyond that junction the water abruptly takes on an opaque turquoise tone.
Laboratory studies carried out in 2013 showed that the change has a physical rather than a chemical cause: suspended aluminosilicate particles in the water grow in size as the more acidic creek mixes with the other stream, and at their enlarged diameter they scatter light through a phenomenon physicists call Mie scattering.Mie scattering by aluminosilicate particles The river therefore appears blue because of the way these tiny mineral particles interact with sunlight rather than because of a blue dye or dissolved pigment.
Waterfall, lagoon and hot springs along the trail
The main walking route through Tenorio Volcano National Park, signposted as “Misterios del Tenorio”, threads from the entrance through rainforest to several named viewpoints on Rio Celeste.Misterios del Tenorio trail One of the best known is the Rio Celeste Waterfall, where the river drops in a single fall of around 30 m (about 98 ft) into a blue pool enclosed by steep, forested slopes.Rio Celeste Waterfall height
Further along the path lie other marked spots that reveal different facets of the river. La Laguna Azul is a small section where the water slows and deepens, intensifying the colour into a compact basin surrounded by low vegetation.La Laguna Azul description At another point, fissures in the riverbed release hot water and gases, forming bubbling patches known locally as “borbollones” that remind visitors that the river runs across an active volcanic complex.
Visiting Rio Celeste: what travellers from Western Europe should know
- Rio Celeste lies inside Tenorio Volcano National Park in northern Costa Rica, between the small towns of Bijagua and Upala in Guanacaste and Alajuela provinces.
- The main approach uses a forest trail with an earthen surface that can be muddy, along with a stairway of many steps down and back up at the waterfall section.
- The park sits in humid tropical forest at low to moderate elevation, and rain showers can leave sections of the path slippery underfoot.
- Spanish is the official language and the currency is the Costa Rican colón.
- Entry requirements depend on your nationality; UK travellers can check the FCDO travel advice at gov.uk/foreign-travel-advice, Irish travellers the Department of Foreign Affairs at ireland.ie.
Searching for Rio Celeste on social platforms
These links open searches for Rio Celeste on each platform.
Frequently asked questions about Rio Celeste
Where is Rio Celeste?
Rio Celeste is a river and waterfall inside Tenorio Volcano National Park in northern Costa Rica, between Bijagua and Upala in Guanacaste and Alajuela provinces.
What can visitors expect on a walk along Rio Celeste?
Visitors follow a forest trail to viewpoints over a sky-blue river, a waterfall, La Laguna Azul and areas of bubbling thermal water, with the colour changing along the route.
What makes Rio Celeste distinctive compared with other rainforest rivers?
Rio Celeste is distinctive because its blue colour appears where two clear streams meet and suspended mineral particles scatter sunlight, turning an otherwise ordinary river an opaque turquoise.
