A nozzle for generating a cavitating jet or a naturally pulsed jet of pressurized liquid, the nozzle having a body comprising: a main channel (12, 14, 16, 20, 18, 22) extending through the body, the main channel having a main inlet for receiving the pressurized liquid, a converging section downstream of the main inlet, a throat downstream of the converging section, and a main outlet for discharging the pressurized liquid from the nozzle, the main channel including a mixing chamber disposed between the inlet and the outlet and downstream of the throat; a flow-reversing channel (24, 26, 28, 29) having: a first liquid-diverting inlet (24a, 26a) upstream of the throat for diverting a portion of the pressurized liquid from a main stream flowing through the main channel; and, for generating the cavitating jet, a reverse-flow outlet (28a, 29a) connected to the mixing chamber for discharging a reverse flow of pressurized liquid into the mixing chamber to thereby create shear forces between the main stream and the reverse flow that generate cavitating bubbles in the main stream of pressurized liquid in the mixing chamber, thereby generating the cavitating jet, or, for generating the naturally pulsed jet, a reverse-flow outlet (28a, 29a) connected to the mixing chamber for discharging an angled reverse flow of pressurized liquid into the mixing chamber at an angle relative to the main stream to thereby intermittently interrupt the main stream, thereby generating the naturally pulsed jet. a main channel (12, 14, 16, 20, 18, 22) extending through the body, the main channel having a main inlet for receiving the pressurized liquid, a converging section downstream of the main inlet, a throat downstream of the converging section, and a main outlet for discharging the pressurized liquid from the nozzle, the main channel including a mixing chamber disposed between the inlet and the outlet and downstream of the throat; a flow-reversing channel (24, 26, 28, 29) having: a first liquid-diverting inlet (24a, 26a) upstream of the throat for diverting a portion of the pressurized liquid from a main stream flowing through the main channel; and, for generating the cavitating jet, a reverse-flow outlet (28a, 29a) connected to the mixing chamber for discharging a reverse flow of pressurized liquid into the mixing chamber to thereby create shear forces between the main stream and the reverse flow that generate cavitating bubbles in the main stream of pressurized liquid in the mixing chamber, thereby generating the cavitating jet, or, for generating the naturally pulsed jet, a reverse-flow outlet (28a, 29a) connected to the mixing chamber for discharging an angled reverse flow of pressurized liquid into the mixing chamber at an angle relative to the main stream to thereby intermittently interrupt the main stream, thereby generating the naturally pulsed jet. a first liquid-diverting inlet (24a, 26a) upstream of the throat for diverting a portion of the pressurized liquid from a main stream flowing through the main channel; and, for generating the cavitating jet, a reverse-flow outlet (28a, 29a) connected to the mixing chamber for discharging a reverse flow of pressurized liquid into the mixing chamber to thereby create shear forces between the main stream and the reverse flow that generate cavitating bubbles in the main stream of pressurized liquid in the mixing chamber, thereby generating the cavitating jet, or,