What factor can significantly affect a diver's ability to equalize pressure?

The factor that significantly affects a diver's ability to equalize pressure is ear and sinus health. This is because the ability to equalize pressure relies heavily on the functioning of the Eustachian tubes, which connect the middle ear to the throat. If a diver has a pre-existing condition such as sinusitis, allergies, or an ear infection, these issues can obstruct the Eustachian tubes and make equalization difficult or even impossible.

Healthy ears and sinuses allow for the effective management of pressure differences when descending or ascending in water. Divers must routinely clear their ears, and if the sinus or ear passages are blocked, it can lead to barotrauma, which is painful and can cause serious injury.

Diving experience level and the type of diving equipment used may influence comfort and technique, but they do not inherently determine the physiological ability to equalize pressure as directly as the condition of the ears and sinuses. Water temperature can impact a variety of factors, including thermal comfort and risk of hypothermia, but it does not play a significant role in equalization. Therefore, maintaining good ear and sinus health is crucial for safe diving practices.