Underwater vision

Underwater Vision

A bifocal mask used for underwater vision.

Underwater vision refers to the ability to see clearly beneath the surface of water. This capability is crucial for various aquatic activities, including scuba diving, snorkeling, and underwater photography. The human eye is not naturally adapted for clear vision underwater due to the refractive index of water, which differs significantly from that of air.

Human Vision Underwater

When humans open their eyes underwater, the light is refracted differently than in air, causing images to appear blurry. This is because the cornea, which is responsible for most of the eye's refractive power, is bypassed by the water. As a result, the lens of the eye must do all the focusing, which it is not capable of doing effectively without the aid of corrective lenses.

Corrective Measures

To compensate for the refractive differences, divers use diving masks that create an air space in front of the eyes. This allows the cornea to function as it does in air, restoring clear vision. Some masks, like the one shown in the image, are equipped with bifocal lenses to assist with both distance and close-up vision, which is particularly useful for reading gauges or cameras.

Adaptations in Other Species

Many aquatic animals have evolved specialized adaptations for underwater vision. For example, fish have spherical lenses that provide excellent focus underwater. Marine mammals such as dolphins and seals have eyes that can adjust to both air and water environments, allowing them to see clearly in both.

Related Pages

• Scuba diving
• Snorkeling
• Underwater photography
• Diving mask
• Refractive index