Abstract: The present invention relates to a method of detecting and locating fresh water springs at sea essentially by taking salinity measurements and by methods and installations for collecting the fresh water. The collection installations comprise an immersed bell-shaped reservoir (10) containing and trapping the fresh water (2) in its top portion, and a pumping system for taking fresh water (2) and delivering the fresh water (2) via a delivery pipe (12), characterized in that the circumference of the bottom end (102) of the reservoir (10) and/or the circumference of the bottom end (61) of a chimney (6) inside the reservoir (10) and open at its top end and surrounding the fresh water resurgence (21) in part and preferably in full, follow(s) closely the outline of the relief of the bottom (4) of the sea so as to provide leakproofing between the circumference(s) and the bottom (4) of the sea.