What is the recommended action if a diver notices a change in ear pressure during ascent?

If a diver notices a change in ear pressure during ascent, the recommended action is to descend slightly to relieve pressure. This is important because as a diver ascends, the pressure decreases, which can lead to discomfort or potential injury to the ear, specifically barotrauma. By descending slightly, the diver can equalize the pressure in their ears to match the external environment and alleviate the discomfort.

This approach effectively allows for the pressure that has built up in the middle ear to equalize with the surrounding water pressure, helping to prevent injury. It's a critical skill for divers to manage pressure changes appropriately to ensure their safety and comfort while diving. Other methods of equalizing ear pressure, such as using the Valsalva maneuver or other appropriate techniques, are also recommended if discomfort arises, but descending slightly is often the most immediate solution to relieve pressure.