Why do objects look blurry underwater?
Show answer & explanation
Answer: Cornea loses refractive power
Water blocks light rays — Wrong. Water doesn't block light. Blurriness happens because water's refractive index is close to the cornea's—light doesn't bend enough at the eye surface.
Cornea loses refractive power ✓ — Correct! In air, the cornea (curved front surface) refracts light significantly because of the large refractive index difference with air. Underwater, water's refractive index (~1.33) nearly matches the cornea's (~1.38), so light barely bends entering the eye. Result: insufficient focusing power, blurry vision. Goggles restore the air-cornea interface!
Water pressure distorts vision — Wrong. Pressure doesn't cause blurriness. The issue is optical—water's similar refractive index to the cornea eliminates the needed light-bending at the eye surface.
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