Which of the following factors does NOT influence visibility underwater?

The type of diving gear does not have a direct influence on the visibility underwater. Visibility is primarily affected by external environmental conditions rather than the equipment a diver uses.

Factors such as distance from the surface can play a role since light diminishes with depth, affecting how far one can see. Suspended particles in the water can cause turbidity, obstructing vision and reducing visibility. The nature of the light source is also crucial; for instance, the type of light (such as white light versus colored lights) impacts how far and clearly one can see underwater.

In contrast, while diving gear may enhance a diver's comfort or safety, it does not alter the conditions affecting visibility itself. Therefore, type of diving gear is correctly identified as the factor that does not influence underwater visibility.