What is decompression sickness?

Decompression sickness (DCS; also known as divers’ disease, the bends or caisson disease) describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurisation. DCS most commonly refers to a specific type of underwater diving hazard but may be experienced in other depressurisation events such as caisson working, flying in unpressurised aircraft, and extra-vehicular activity from spacecraft.