Cousteau graduated from the Naval Academy and chose to serve in the French Navy's information service. This position allowed him to travel and gain a broad range of experiences.

A car accident nearly ended Cousteau's life and severely injured his arms. During his recovery, he turned to swimming as therapy, which intensified his love for the sea and encouraged him to find ways to explore it more effectively.

During World War II, Cousteau served in the French Navy, initially for the Vichy government. He participated in espionage activities for the French Resistance and was awarded the Legion of Honor and the Croix de Guerre for his service.

After the war, Cousteau continued his naval career, using his position to further his underwater explorations and research. He began experimenting with underwater photography and filmmaking, laying the groundwork for his future documentaries.

Cousteau formally retired from active service in the French Navy, although he remained a Reserve Officer. This allowed him to dedicate himself full-time to oceanographic exploration and filmmaking.