In 1983, five men were killed in less than a second during the Byford Dolphin diving accident in the North Sea. The cause was ΔP (delta-P), the sudden difference in pressure between two spaces. During a routine operation, a clamp connecting a pressurised diving chamber to a diving bell was opened incorrectly. The pressure inside dropped almost instantly. The change was so extreme that the four saturation divers inside the chamber were killed immediately. A fifth man, a diving tender standing nea