Nausea at Depth

Diver surfaces after experiencing symptoms without an obvious cause

Reported Story

Nausea caused a diver to halt her descent at 82 fsw (25 msw) during a group deep dive to 131 fsw (40 msw) at a familiar dive site. She alerted her buddy and they both agreed to abort the dive and took over ten minutes to ascend to the surface. They did not alert other divers of the problem, and the rest of the dive group continued with their dives.

At the surface, dive boat personnel assisted with the setup of oxygen and administered it to the nauseated diver in an attempt to relieve her symptoms. The other divers in the group were not recalled, and completed their dives over the next 20 minutes. Once all the divers had completed their dives and were aboard, the dive boat headed to the shore. On the way to shore, a surface breaking of fish were seen and several divers requested to enter the water to snorkel and view the fish. The dive boat steersman agreed, provided they were quick, as the diver was still feeling nauseated and was still on oxygen. After five minutes, the boat resumed heading to shore.

The nauseated diver was instructed to avoid exertion and was monitored at shore. After 30 minutes, the diver reported still feeling unwell and was taken to be medically evaluated. She was placed under 24-hour observation and was released in good health with no treatment required. No cause was discovered for nausea. The breathing gas in the diver’s tank was analyzed and no contaminants were detected. The regulators were also checked and no issues were found. The ill diver did not experience any seasickness or other symptoms throughout the incident.


Calling the dive soon after experiencing symptoms allowed the diver and his buddy time to safely ascend to the surface and promptly assess his medical status. Oxygen administration was timely at the surface; however, there were several delays in getting the ill diver to shore to be medically evaluated. Ideally, medical evaluation should be received as soon as possible. In this case, the diver’s symptoms were nausea without an obvious cause, such as sea sickness or dive profile. This could indicate a non-dive related health issue for which medical evaluation should still be sought as soon as possible.

Analyzing the breathing gas after the incident was useful in ruling out contamination as a possible cause. The diver’s health status improved without any additional symptoms or necessary treatment. In this case where the cause of the nausea is unknown, it is recommended to be medically evaluated before returning to diving and to continue to monitor for any reoccurring episodes.

Brittany Trout