There are no tracks leading to this hole in the middle of an ice-coated lake, so who made the hole?
Here are some nearby clues:
A well-traveled path to a hole in the bank of the lake.
Scat full of fish scales and fragments of crayfish exoskeletons.
And sliding trails into the water.
These are all signs of…
River otters!
The otters seem to be able to tell where the ice is thinnest in the lake and come up from underneath to keep it open. They use these holes for breathing breaks and also as a place to eat their aquatic catches.