Question

What term refers to the coldest and densest zone, deep below the surface of a lake?

Answer 1

Profundal 

profundal zone is the coldest and deepest zone 

Answer 2

Answer: Hypolimnion

Explanation:

The hypolimnion layer is found in the dense region of lake. It is bottom layer of water in a thermally stratified lake.

This region has lowest oxygen concentration,and it lies below the thermocline.

It is the deepest and coldest layer found in lake. It has very less oxygen and maximum amount of sediments is also found there.

There reaches no light so photosynthesis id not possible there. The temperature there is almost 4 °C throughout the year.