You don't usually think of an entire lake as something that just disappears. But every year, one in the mountains of Oregon - aptly called Lost Lake - gets sucked down a lava tube, leaving only a meadow behind.
And no one knows where the tunnel leads, or where the water goes.
How this happens is pretty cool. Tubes dot this particular part of Oregon; they're created when lava hardens at the surface but keeps on flowing underneath, the Bend Bulletin explained. If it's still chugging along underground and flows out before it hardens, a channel is left behind. Add in a little bit of erosion or a volcanic eruption, and an open hole is born.
And it's a perfect place for a lot of water to disappear into.
In winter, the Cascades' snow freezes and Lost Lake runs dry. When the snow melts in summer, streams brimming with the melt fill it back up. But then it reaches the north side, and drains like a great bathtub through the tube.
It has been around as long as the locals can remember. In fact, Native Americans in the Cascades region first gave it the name Kwoneksamach, or "unknown." Europeans came to the area in the 1870s, lost their way, and christened it accordingly, the Washington Post reported.
But the mystery remains unsolved. The pervading theory is that it feeds an aquifer beneath the mountains and replenishes groundwater, feeding springs. Interestingly, the region isn't suffering from drought like its neighboring counties, the Post pointed out.
So it would seem that the lava tube is serving an important purpose, in addition to being quite an interesting and bizarre little quirk of nature. But for some reason, some people have insisted on plugging up the great bathtub drain - and they've been pretty creative about it.
Willamette National Forest Spokeswoman Jude McHugh said the U.S. Forest Service has found car parts, engine and more in the hole, which officials believe were put there to keep the lake from disappearing. Obviously, this is a bad idea.
"If anyone was ever successful at plugging it — which we're not sure they could do — it would just result in … flooding, and the road; it's an important part of how the road was designed."