At Lost Lake in Willamette’s national park in Oregon, a strange nature phenomenon is acting out every year for as long as people can remember.

At this certain time of the year, the lake is swallowed by a big hole. Where the water goes? No one really knows, The Bulletin writes.

Here’s the hole that fascinates an entire world.

A video of the phenomenon.

The explanation is lava streams. They are formed during volcanic eruptions when the lava flows beneath the surface. When the lava travels underground it can build tunnels. And when the tunnels or the streams collapse it forms a hole. Take a look at the illustration below.

According to Jude McHugh, spokesperson for the national park, the water from Lost Lake transpire down in the earth through the lava-stream, which fills up the other water sources in other places in the forest. Water sources that work as drinking water for the societies surrounding Lost Lake.

Isn’t our nature amazing?