Local lake that is the definition of thalassophobia.

I've been afraid of deep water as long as I can remember, it's irrational but I can't help it. Last year on a fishing trip was when it really started to bother me. Quanja Lake is located on a Native reservation, and according to local legends is bottomless with a serpent living in it. Obviously I don't believe in legends like this, but when I arrived at the lake it was clear how the legends might have started. The shores were sandy and inviting, but about 50 feet out they dropped off into inky blackness. It was a shocking contrast, and there was a definite ring around the lake where it changed colour.Here is a google earth screenshot of the lake.Another picture looking down from one of the cliffs.The most peculiar thing about this lake is the sand bottom. Most lakes that have steep dropoffs in my experience are rocky, like underwater cliffs. If they are sandy then eventually over time the currents smooth out the dropoffs and you get a gradual slope. The only thing I could think of to explain it was that the lake was like a giant sinkhole, draining to the middle and keeping the dropoffs steep.I didn't see any monsters, but I did run out of 200 feet of line trying to get to the bottom in the middle. 10/10 would not make a return trip.