Reflections in lake vs swimming pool

Question

Why do lakes reflect objects better than swimming pools? Is it because light reflects from light but not dark bottoms, thereby obscuring reflection?

Answer 1

I think your suggestion is right. If you look out of the window in a train that drives into a tunnel, you suddenly see yourself in the window. This is not because the reflection coefficient of the window increased, but because all the light passing through the window from the outside is not there anymore. If the bottom is light (pool) you see that light stronger than the reflected light. But the reflection from the water-air interface is the same in both cases, assuming that both cases are pure water.