The scenic Medicine Lake in Jasper National Park, Canada is not what we can call a normal mountain lake.
Every fall, its water is literally swallowed by underwater sinkholes.

During summer, visitors believe that they are walking around a normal lake as it is filled up with glacier melt water. But they are wrong! In fall and winter the lake almost disappears and transforms into a mudflat scattered by water pools interconnected by a stream.
But there is no visible channel draining the lake – so where then does the water go?
The water is drained out of the bottom like a bathtub without a plug. The Maligne River pours into the lake from the south and drains out through sinkholes in the bottom. The water then streams through a cave system formed in the slightly soluble limestone rock, surfacing again in the area of Maligne Canyon 16 kilometers downstream. This is one of the largest known sinking rivers in the Western Hemisphere and may be the largest inaccessible cave system anywhere in the world!

How to explain the mysterious process?
Summer melt water coming into the lake exceeds the capacity of the sinkholes to drain it. Decreased melt water in the late summer and fall means that the lake’s sinkholes can drain the lake faster then the Maligne River can fill it. This creates the disappearing lake phenomena.

Aboriginal peoples called the lake Medicine because of its seemingly magical powers, and the United Nations created the Rocky Mountain Parks World Heritage Site partly because of this unique drainage system.
Have you already visited this mysterious place in Canada?
[…] linked to phenomena hidden underground? Is permafrost altering the water balance in the lake? Is a giant sinkhole draining the lake? I don’t know, but there is something going on […]