Anyone who wants to study fish must become a fish themselves. This was claimed and proven by the brilliant marine researcher Jacques Cousteau, who explored and described underwater life in a way that no one else has. He began diving and experimenting as a child. The stories of Indians breathing underwater through reeds captivated him. Thus, he developed diving with oxygen equipment and became one of the greatest pioneers in exploring the depths of the oceans. Antje Boetius also developed an interest in the sea as a child. Her grandfather was a captain and often shared his experiences at sea. Today, the marine researcher is a professor of geomicrobiology at the University of Bremen and explains in this exciting adventure feature what happens to our bodies while diving.