Thanks for the corrections: So the bubbles are not a vacuum but low-pressure vapor and cavitation is the name for the collapse, not the bubble itself. And this can only happen in liquids where there is a potential phase transition. I've got a little marine knowledge but my physics is lacking so I appreciate the clarification!

I assumed cavitation had similar parallels in air propellers with high tip speeds (as you approach the speed of sound) but seems that is a different effect?