About 2 hours east of Portland, Oregon, there is a lake. Or at least, sometimes there is a lake.
Lost Lake, as the body of water is known, only exists for as long as it takes for all the water to drain into a hole. Then it becomes a meadow until the next year, when winter precipitation melts and runoff fills it back up again. Here’s a video:
We know what the hole is: a lava tube, which formed when molten rock hardened near the surface but continued flowing below. And according to The Bulletin, there are similar lava tubes in nearby Fish Lake.
What is less clear, however, is where the hole leads. Jude McHugh, spokeswoman with the Willamette National Forest, told The Bulletin that the hole probably sends the water down into an underground aquifer, which then feeds mountain springs. However, ultimately no one is really certain where the tube, and the water, go.
— Jim Dalrymple II