Inspired by the potential of underwater exploration and the need to understand marine environments more intimately, Cousteau conceived the idea of creating underwater habitats where humans could live and work for extended periods.

Conshelf One, also known as 'Diogenes,' was the first underwater habitat established by Cousteau's team. Two aquanauts lived in the habitat for a week at a depth of 10 meters (33 feet) off the coast of Marseille, France. This experiment proved the feasibility of underwater living.

Conshelf Two, or 'Starfish House,' was a more ambitious project. It involved a larger underwater habitat with a garage for a diving saucer, a pen for marine animals, and a workshop. Five aquanauts lived and worked there for a month at a depth of 11 meters (36 feet) in the Red Sea.

Conshelf Three was the deepest and most technologically advanced of the Conshelf projects. Six aquanauts lived in a spherical habitat at a depth of 102.5 meters (336 feet) off the coast of Cap Ferrat, France, for three weeks. This experiment focused on using a simulated oil rig to understand the challenges of deep-sea industrial operations.

After Conshelf Three, Cousteau's focus shifted towards filmmaking and conservation. While the Conshelf projects didn't lead to widespread underwater colonization, they provided valuable insights into human physiology, marine technology, and the challenges of living and working underwater.