Temp range of the Twilight Zone?
Crazy as it sounds the water temperature ( but not the pressure) of really deep oceanic waters cannot normally go below 32 degrees. It does decrease with depth, but say, l0 grand down, the water temperature is just above the freezing point. owing to immense hydrostatic pressure, it cannot form Ice . The subject is discussed in some detail in Heuvelmans" tome on the Sea Serpents along the lines of a habitat feasibility study.