The Darkness is the Partial or Total Absence of Light.
The ability to control the darkness is the ability to command the light, and the ability to control the waters is the ability to delimit their boundaries and make them useful rather than destructive; useful for sustaining life.
Darkness" in both the Old Testament and New Testament" is an evocative word. If light symbolizes God, darkness connotes everything that is anti-God: the wicked Judgment, and death. Salvation brings light to those in darkness.
Although darkness is opaque to man, it is transparent to God Indeed, God can veil himself in darkness at moments of great revelation