On the other hand, a large nozzle improves the amount of water flowing through the pump, which improves static thrust, and provides a less stiff load on the engine, allowing it to rev up faster. You have to make a compromise choice between the holeshot and top speed. Aftermarket nozzles are available with a larger nozzle to improve the bottom end, and some are also available with replaceable inserts to allow you to tune your holeshot vs. your top speed. Finally, lets talk about cavitation. Cavitation is just boiling water.
Water can boil at any temperature.
All liquids have something called vapor pressure. As the temperature goes up, so does the vapor pressure. Water just has a lot less vapor than gasoline. A liquid boils when it gets so hot that it's vapor pressure reaches the pressure surrounding it. In a pot of water, that is the pressure of the atmosphere pushing down on the water, about 14.7 psi.