Things get very bad, very quickly for people in cold water. Just minutes after total submersion, heart and brain activity stop. But the cold also protects. If rescuers can reach a drowning victim in less than 90 minutes, it's possible to resuscitate, often with no long-term ill effects. Inspired by this fact, Duncan Winsbury, a former station manager at the Fire & Rescue Service in Derbyshire, England, set out to build a robot that could find and retrieve cold-water drowning victims fast.