Which body of water in Oregon vanishes in summer and turns into a meadow?

During the rainy fall and winter, most Oregonians probably don't give much thought to Lost Lake, a shallow lake surrounded by pine trees that sits near a highway.

But drivers might do a double take during summer. During the dry months, the 85-acre (0.34 square kilometers) lake vanishes and turns into a meadow.

The reason? Two hollow lava tubes at the bottom of the lake are constantly draining the lake dry, much like a bathtub left unplugged.

"The lake bed begins to fill in the late fall, when the amount of rain coming in starts exceeding the ability of the lava tubes to drain off the water," said Jude McHugh, a spokeswoman for the Willamette National Forest in Oregon. "And it continues to fill all winter long in a series of rain or snowstorms."

As the rainy season peters out, the 9-foot-deep (2.7 meters) lake loses its water source, and water disappears down the lava tubes until it's gone, McHugh said. The lake's watery boom-and-bust cycle repeats itself every year, she added.