Most of their lakes are shallow glacier cut bird baths.
Here is a local news story on the incident with more information and a pic of where they ran off into the water. It must have been really bad weather not to see what they ran off into.
FWIW, this accident occurred on a boat ramp on the ocean.
Sebago Lake, Moosehead, Rangeley have some depth over 20’, unless you are talking only *mean depths.*