In Super Mario Sunshine, the FLUDD nozzle that lets Mario hover is the Hover Nozzle.
FLUDD, short for Flash Liquidizer Ultra Dousing Device, is Mario’s water-powered robotic backpack. Professor E. Gadd created it to spray water, clean goop, activate mechanisms, and help Mario navigate Isle Delfino. The Hover Nozzle uses water to keep Mario suspended briefly in midair, making it useful for crossing gaps and correcting jumps.
Mario begins with the Squirt and Hover Nozzles. Later, he obtains the Rocket Nozzle, which launches him vertically, and the Turbo Nozzle, which gives him great speed and lets him skim across water. These additional nozzles replace the Hover Nozzle when equipped, so they are not separate starting abilities.
A common mix-up is calling the Hover Nozzle the “Spray Nozzle.” Spraying is the basic function of FLUDD’s Squirt Nozzle; hovering is specifically the job of the Hover Nozzle. Some secret stages remove FLUDD entirely, forcing Mario to rely on conventional platforming.