I had the same problem and ran around in circles for hours. AND HOW IS THAT HOLE A HOLE in any shape or form I ask?!!?!?!?!
EDIT: uh what I meant to say is that I was looking for a well or a rock formation that resembles such. How my comment came out sounded so wrong in so many ways O_O()
I believe that a "fishing hole" refers to a hole beneath the water's surface, around which fish gather. The deeper waters are often more cool than the more shallow waters, and in the depths of the submerged hole, there is an abundance of plants -- and, of course, camouflage from water-dwelling predators.
In this sense, a "fishing hole," as far as the look of the lake is concerned, should look no different from any other lake. It would be quite easy fishing if it was just a small hole in the ground -- almost like shooting fish in a barrel! XD
_______ ~ _______ surface
\ _____/ ~ \______/ under water
The first "picture" is a lake with a fishing hole; the second (after the ~) is one without -- note that, as far as the above-water fisherman is concerned, one lake looks just like the other.