During World War II, a group of scientists conducted over 600 experiments on themselves to help divers and submariners. Diving in the 1940s was popular but required bulky suits and large helmets, as well as constant tethering to boats for air supply. The sinking of the submarine Thetis in 1939, where 99 people died of unknown causes, highlighted the inadequacies of breathing support equipment for underwater mobility. An investigation into the tragedy led scientist John Burdon Sanderson Haldane to conduct experiments on himself and colleagues in a high-pressure chamber. These experiments focused on the effects of different gases and pressure levels on the human body.

Through their experiments, Haldane and his team discovered the dangers of excess CO2, oxygen toxicity, and nitrogen intoxication in high-pressure environments. They also worked to find the ideal mixture of oxygen and air for divers and submarine crews to breathe without side effects. These experiments led to the development of breathing support equipment used by the British Navy during World War II.

The dangerous experiments conducted by Haldane’s group not only aided in the D-Day campaign but also contributed to the scientific foundations of modern scuba diving. Their work, although risky, paved the way for advances in underwater breathing technology that continue to save lives today.

During World War II, a group of scientists conducted over 600 experiments on themselves to help divers and submariners overcome challenges posed by their bulky suits and large helmets. Experts have long been aware of decompression sickness caused by nitrogen bubbles forming in blood when divers ascend too quickly from deep dives which can be fatal in severe cases. This condition was highlighted after an investigation into an incident where 99 people died aboard Thetis submersible in 1939 due to unknown causes while it was sinking during World war II