In the first days after the accident at the Chernobyl nuclear power plant, firefighters fought the blaze by pouring water over the fire and sprinkling the ignition chambers with sand and pebbles. This helped to prevent potentially terrible consequences. Five days later, however, the situation became more complicated as the reactor continued to melt, gradually destroying the concrete slab beneath which a huge pool of water lay. The contact of the roasted mass with the water could release a giant cloud of radioactive water vapor into the atmosphere. To prevent a possible disaster, the pool had to be drained immediately so the situation required to involve people with scuba diving skills because the access to the resistance taps was underwater. Three people were involved into this operation. Divers knew that they would be exposed to radiation in the pool, but safely reached the shut-off valves. It took them a few tries, but they were up to the task, and their feat became a legend.