SDI Open Water Scuba Diver Practice Exam

Which of the following actions can help prevent mask fogging?

1. Using spit or defogging solution

2. Wetting the mask with saltwater

3. Using a tinted mask

4. Avoiding wearing a mask altogether

The correct answer is: Using spit or defogging solution

Using spit or a defogging solution is an effective method to prevent mask fogging while scuba diving. When you apply spit or a specialized defog solution to the inside of your mask lens, it creates a thin film that helps to reduce the surface tension of the water. This film prevents water droplets from forming on the lens, which is what causes fogging. Mask fogging occurs due to the temperature difference between the inside of the mask and the cooler water outside. When the warm air from your breath comes into contact with the cooler surface of the mask, condensation forms. The application of spit or a commercial defogger mitigates this effect and maintains a clear view underwater, enhancing safety and enjoyment during the dive. While wetting the mask with saltwater might provide a temporary solution, it does not effectively prevent fogging as it does not create the same protective film. A tinted mask has benefits such as reducing glare but does not address fogging. Avoiding wearing a mask altogether is not a practical or safe option for scuba diving, as visibility is crucial for safety. Thus, using spit or defogging solution is the recommended preventive action against mask fogging.