Which of these is the largest? a. The surface zone b. The mixed layer c. The deep zone d. The bathypelagic zone Solution c. The bathypelagic zone ranges from 1000-4000m; that of the surface zone. i.e of epipalezic zone is of 200m, the mixed layer or twilight or mesopalegic zone is of 200-1000m, and the deep zone, hedapelazic zone is of approximately 5000m..