At the bottom of the mixed layer, because this is where the mixed layer is seperated from the calm deep water below it.

The transition layer between the mixed layer at the surface and the deep water layer.

many moons

Mixed Layer

Main Thermocline

Deep Water Layer

the first layer is the surface layer it is nice and warm and mixed with the waves.

the next layer is the thermocline it is just warm not any thing special.

the next is freezing cold i would not want to go there.