Hi @UltraFred,
Our switch should be safely operable under water, but the rotating plug is a screw that’s not limited / fixed in place, so if you unscrew it too much it will come out completely, and the water will go past it and bear directly against the internal button (which is not designed to be watertight or pressure rated).
If this is for an application where it’s obvious when the switch has been turned off then that should be fine (because you can stop turning as soon as it’s off), but if the application gives no sign when the switch is or isn’t connected then there’s a bit more risk of accidentally unscrewing it too much (although that should still be pretty hard to do unintentionally / without realising).