Click play on the video above, and it takes a fraction of a second to realize something isn’t right. You’re walking on a rainforest trail, with a clear path and vegetation, but the light is tinged with green. Everything, from the camera’s forward movement to the swaying of the leaves, happens just a bit more slowly than it should. Eventually, the camera tilts up to reveal that the sky has a strange ceiling. But it isn’t the sky after all: The trail is underwater!

The footage was taken on February 2, 2018, at Recanto Ecológico Rio da Prata, a nature reserve in Jardim, Brazil. People go to the park to hike, horseback ride, birdwatch, and scuba dive—but not, generally, all on the same path. When a park guide went to monitor the site and found that this hiking trail suddenly required a snorkel, he decided to take out his camera.

So how did this happen? The park is located at the junction of two rivers, da Prata and Olho D’Agua. According to the video description, the heavy rains in early February caused the Rio da Prata to dam up, raising the level of the Olho D’Agua in turn. The water’s clarity likely results from a combination of factors, including its source—springs that wind through a limestone karst—and the fact that visitors are encouraged not to kick up sediment.

The resulting video is dreamlike. Land plants stoically bear the weight of the water, and a bridge, conquered by the river it once crossed, now seems to go nowhere at all. Occasionally, a couple of fish drift by, perhaps confused by their new surroundings.

By the next day, the waters had receded again. And—in case you were worried—the reserve assures that despite the flooding, “all the tourists left satisfied.”