The first time you see the Río Celeste (“Sky-Blue River”) it is hard to believe the color is real. Its water is such an intense turquoise that many photos look edited. The river flows inside Tenorio Volcano National Park, between the cantons of Guatuso and Upala, in northern Costa Rica.
Why is it blue?
For a long time people said the color came from minerals such as copper or sulfur. Research by the University of Costa Rica and the National University showed a different explanation: at a spot called Los Teñideros (“the dyers”), two streams meet, the Buenavista River and the Agria creek. When they mix, the acidity of the water changes and tiny mineral particles (aluminosilicates) grow larger. Those particles scatter sunlight and reflect mostly blue light.
That is why the color changes with the weather: after heavy rain the water can look cloudy, and on sunny days the turquoise shines even more.
What to see along the trail
- The waterfall: a drop of about 30 meters into a blue pool, reached by a long staircase.
- The Blue Lagoon: a calm pool where the water turns an even deeper color.
- Los Borbollones: bubbles of volcanic gas rising from the riverbed.
- Los Teñideros: the exact spot where you can see the water change color.
| Location | Guatuso and Upala, Alajuela |
| Protected area | Tenorio Volcano National Park |
| Trail | About 6 km round trip, muddy with slopes |
| Important | Swimming in the river is not allowed |
Tips for your visit
- Wear shoes or boots with good grip; the trail is usually muddy.
- Arrive early: entry has set hours and limited capacity.
- If it has rained a lot, the color may not look the same. Keep your plans flexible.
- Check the park’s status on the official SINAC website.
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