When a person's world suddenly collapses, the experience often feels like being plunged into sudden darkness or swept away by a violent flood. In his address to Job, Eliphaz uses this intense imagery of shadows and drowning to explain the grim reality of Job's situation.
The primary approach among commentators is that this darkness and rushing water serve as metaphors for sudden, overwhelming suffering. The darkness represents a state of deep fear and confusion. A person's mind becomes clouded, making them unable to spot the traps laid out before them or find a way to stay safe. At the same time, the floodwaters symbolize intense pain that completely covers a person, leaving no way to escape [מצודת דוד, ביאור שטיינזלץ]. These troubles strike suddenly as a punishment for past wrongs. Because the disasters pull a person under before they can even understand what is happening, Job is told he should not be surprised by the tragedies that have ruined his life [רמב״ן]. Furthermore, this serves as a warning to Job not to place his trust in his own physical strength when facing such unstoppable forces [רש״י].
Taking a different direction, other commentators read these images not as physical suffering, but as a sharp critique of Job's spiritual outlook and his doubts about Divine providence. In this view, the blindness mentioned is not Job's inability to see danger, but rather his mistaken belief about what God can see. Because Job watches wicked people succeed, he incorrectly assumes that God's vision and involvement in the world are limited, much like a human's. Just as thick darkness or deep water blocks the sight of an ordinary person, Job wrongly believes that clouds, fog, and shadows stand between God and the earth, preventing Him from seeing human actions [מלבי״ם, אלשיך, אבן עזרא].
A final, unique approach entirely rejects the idea that Eliphaz is criticizing Job for his sins. Instead, Eliphaz is trying to explain exactly why Job cannot mentally grasp the hidden secrets of how God runs the world. Here, the darkness and water represent internal, physical barriers that block clear thinking. The darkness points to deep sadness and inner gloom, while the heavy waters symbolize a sluggish, overwhelming physical state that clouds a person's natural temperament. These internal struggles create a thick wall between the human mind and the ultimate truth. They prevent Job from understanding the ways of God's providence, just as surely as a person standing in pitch blackness or submerged underwater cannot see the world around them [תקות אנוש].