Minerals or other bodies are lifted hydraulically from a region below the surface of a free fluid medium, such as the ocean. An at least partly gas-filled chamber with an elongated conduit extending therefrom is at least partially submerged in the fluid medium so that the conduit extends to the region from which the bodies are to be lifted. The fluid level in the chamber is maintained sufficiently lower than that of the surrounding fluid medium, as by a suction pump exhausting into the medium, such that the fluid pressure corresponding to the difference between the fluid level in the chamber and the level of the medium is at least substantially equal to the sum of the frictional pressure drop of fluid through the conduit and the pressure drop due to the lifting of the bodies in the fluid medium through the conduit. The velocity of fluid flow through the conduit is maintained larger than the steady state sinking velocity of the bodies.