I had seen photographs of Río Celeste online and assumed the colour was enhanced. It is not enhanced. It is exactly that blue — a blue so unlikely that you keep looking at it and looking at it, wondering how any natural process produces something so precise. The hike through the national park is beautiful in its own right, but the moment the river appears through the trees is genuinely one of the most striking things I have ever seen in nature. Worth every kilometre of the drive.

We had done many nature experiences in Costa Rica over the years and thought perhaps nothing would surprise us. Río Celeste surprised us. The colour is a scientific phenomenon — our guide explained the chemistry of it beautifully — but knowing the explanation does not diminish the experience of seeing it. The national park is carefully preserved and quiet, the trail is lovely, and the paperwork requirement (passport numbers for all) is a small price to pay for access to something this extraordinary.

Our children are twelve and fifteen and they have seen a great deal of the world. Both were speechless when they saw Río Celeste. The guide was exceptional — knowledgeable, enthusiastic, and very good at pitching the natural history at a level that worked for everyone. The forest inside Tenorio National Park is pristine and full of life. The lunch afterward was excellent. An early morning and a long drive, yes — and completely worth every minute of both. The best day of our Costa Rica trip.