Towing a camera attached to several fins has shown the occassional presence of a visible tip vortex, usually visibly present on the second half of harder turns, but it will show up after kicking out of a wave at speed and turning the board back to sea paddling too.
When passing through turbulent water from the previous wave the fin tip appears to collect the bubbles and funnel them into a more visible tip vortex, like shown in the photo below, but there are examples of the visible tip vortex occuring in cleaner green water too.
Its not hard to understand how already present bubbles get captured and combined into the visible tip vortex, But:
How do these bubbles form several inches below the water surface in near clean green bubble free water? Separation of flow vs cavitation...... I though the true definition of cavitation could not really occur at surfboard speeds, that enough energy could not be created to form a void.
I've not uploaded any video to youtube or similar at this point but plan to, soon.
I'll search some more videos for examples of clean green water visible tip vortex and take screen shots, the photo below was just convenient to attach at this time