This book documents the exploration and engineering history and potential of two submarine karst springs, Port Miou and Le Bestouan, from the 1970s until now. These springs are the outlets of a vast and deep karst aquifer of more than 1000 km2 near the city of Cassis, France. It presents the latest hypotheses for the hydrological and speleological models of this karstic network explaining the intrusion of saline waters within the system with further applications to other karstic springs in the Mediterranean.