What should be done if a diver starts showing symptoms of decompression sickness during a dive?

If a diver starts showing symptoms of decompression sickness during a dive, the most appropriate action is to recompress or seek medical assistance. Decompression sickness, often referred to as "the bends," occurs when nitrogen bubbles form in a diver's body due to rapid ascension from depth. The symptoms can range from mild to severe, and continuing to dive or ascending too quickly can exacerbate the situation and lead to serious health risks.

Recompression can be performed in a hyperbaric chamber where the diver receives oxygen at pressures greater than atmospheric pressure. This treatment helps to reduce the size of nitrogen bubbles in the body and allows for safe elimination of excess nitrogen. Seeking medical assistance ensures the diver receives appropriate care from professionals trained to handle such emergencies.

In contrast, immediate ascent to the surface or monitoring the diver without action could lead to worsening symptoms or even life-threatening situations. Continuing the dive without addressing the symptoms could result in severe complications. Therefore, taking immediate action to recompress or reach medical assistance is the correct and safest course of action.