What a diver must be able to do for an attack

In scuba diving, compressed air can reach depths of a little more than 50 meters for a short time. In order to get to the Baltic Sea pipelines, on the other hand, the divers have to use so-called mixed gas. Helium is added to breathing air, which consists mainly of oxygen and nitrogen. This is necessary because more nitrogen is dissolved in the blood due to the high water pressure at depth. When surfacing, like opening a bottle of sparkling water, bubbles can form in the blood from which the exchanger can then die. Therefore, at extreme depths, helium is added to reduce the nitrogen content. At the same time, the amount of oxygen must be reduced at depth, because too much oxygen is also harmful here.