There is a doomed lake in the Northwest Territories which will fall off a cliff soon. The record temperatures in the NWT have been melting the permafrost and the cliff close to the lake has been gradually slumping down. There’s only a short width of cliff still holding up the lake. When it slumps, the lake will flood down the cliff. Good picture in this article:
This is happening all over the Arctic, exacerbated by melting permafrost and higher sea levels. Here’s a picture from Shishmaref, Alaska. Entire villages have had to be relocated due to these effects.
I’m curious how long it will be until the cliff collapses. I assume it will be one of those things that happens almost immediately once there’s a breach in the cliff?
The optimist in me says you’re not losing a lake, you’re gaining a waterfall! 
For a very short time but no doubt spectacular for a minute!
Not a good time to be taking subsoil samples IMEIO
I’d expect surfers to be hanging around waiting to catch that one big wave. Or at least some white water rafters, kayakers, or canoers. Really, how many chances are there to do something like that?
Seriously, maybe they should drop some brightly colored floats down there just to track them when it breaks open.