Oxygen, the very thing that gives us life, can also be life-threatening, under certain circumstances increasing the risk for central nervous system oxygen toxicity (CNS-OT) seizure. CNS-OT seizures are a limitation of both hyperbaric oxygen therapy and scuba diving, particularly among Navy SEALS who use closed-circuit rebreathers. Dr. Dominic D’Agostino, an expert in the neuroprotective effects of the ketogenic diet, explains why ketones were investigated as a possible mitigator of CNS-OT seizures. He also summarizes existing research on the effects of exogenous ketone supplements on CNS-OT, describes the potential mechanisms at work, and lists examples of ketones' protective qualities.