Experiments were conducted on the maximum and terminal penetration depths of fountains of light fluid, issuing vertically downwards into quiescent denser fluid. Fresh water jets into saltwater, and hot water jets into fresh cold water were investigated. The source Richardson numbers extended from 0.01 (jets) to 1 (plumes). Circular and three other different shape nozzles have been employed. The normalized penetration depth is constant for jets, while it decays exponentially in plumes. Numerical evaluation of the penetration depth has indicated the need for reevaluation of the entrainment coefficient, in negatively buoyant jets. (C) 2008 Elsevier Ltd. All rights reserved.