This might be old news, i dont know. But i just stumbled upon it on a flight this afternoon and thought i might share it with you guys incase some folks didnt know about it.
There is a 12,000 foot deep crevace with a lake at the bottom of it at these coordinates:
N37' 31.04"
W93' 38.11"
The closest airport is identifier MO3, Stockton airport in missouri. it is right near a lake which seems to spill into this canyon.
go check it out, would be a neet place to set up a cabin haha so long as you had a sea plane to get in and out of there.