Diving with what condition may lead to pain during descent or ascent?

Diving with cold or congestion can lead to pain during descent or ascent because these conditions can affect the body's ability to equalize pressure in the ears and sinuses. When a diver descends, the increasing pressure can create a differential between the outside pressure and the pressure in the body's air spaces, especially in the middle ear and sinuses. If the sinuses are congested due to a cold or allergy, the air cannot move freely, potentially leading to barotrauma, which manifests as pain.

During ascent, if these pressures are not equalized, it can cause discomfort or even injury to the ear drum or other air-filled spaces. Therefore, being aware of congestion is vital for divers, as it significantly influences their ability to handle the pressure changes associated with diving.