photo credit: It's a lake with a drainage hole! YouTube
There is a lake in Oregon that disappears every spring. This ephemeral water feature is aptly called Lost Lake, and its peculiar seasonality is due to a rare geological feature called a lava tube.
Lava tubes are formed when lava cools at the surface, but hot lava still flows beneath. When the hot lava drains away, it leaves an empty hole.
In early spring, the lake fills with water from the snowmelt of the nearby Cascade mountains. This happens faster than the 1.8-meter (6-foot) hole can take it away. In late spring, the lake is suddenly drained and the Lost Lake turns into a peaceful meadow.
You can check out footage of the lake draining below.