Final answer:
A diver should ascend to shallower depths to alleviate the symptoms of nitrogen narcosis, ensuring a slow ascent to prevent decompression sickness, with hyperbaric oxygen therapy as a possible treatment if preventive measures fail.
Step-by-step explanation:
To alleviate the symptoms of nitrogen narcosis, a diver should ascend to shallower depths. Nitrogen narcosis is a condition that occurs at considerable depths due to the increased pressure causing higher concentrations of nitrogen to dissolve in the diver's blood, as per Henry's Law. Ascending reduces the ambient pressure and the amount of dissolved gas in the bloodstream, thereby minimizing the symptoms of narcosis. Additionally, divers must ascend slowly to prevent decompression sickness (DCS), sometimes known as "the bends," which can cause more severe symptoms if the ascent is too rapid. When divers experience DCS, and preventive measures are inadequate, hyperbaric oxygen therapy is often used as treatment.