Also known as 'the bends', decompression sickness is a perilously common affliction in scuba and deep-sea divers. As outlined by Harvard Health, the condition is "caused by a rapid decrease in the pressure that surrounds you"; this happens when the diver resurfaces too quickly and causes nitrogen bubbles to form in the blood, leading to symptoms from dizziness and joint pain, and in dire cases like Duffy's, death.