I think lokipagan has confounded the ability to see a corpse with whether you can see a corpse at the moment. In an L shaped pool I can see the corpse going in or out of the pool or if I near the bend. I would need a pool big enough that I don’t have the physical ability to see it or discern corpse from flotsam.
A special situation in which, until observed, there both is and isn’t a corpse in the pool. Interesting.