Every year the water from a lake in Oregon disappears down a 6ft-wide plug hole. The natural phenomenon causes Lost Lake to turn into a meadow in the summer. It is caused by tunnel-like lava tubes, of which there are many nearby. There have been several attempts to block up the hole and forest rangers have found car parts and other debris that people threw into it. If anyone were ever successful at plugging it, which might be very hard to do, it would just result in the lake flooding, and the roads near by.
Lake Drains Like a Bathtub in Oregon
Video by bendbulletin.com