I'm playing the re-release of Super Mario 64 in Super Mario 3D All-Stars. In Jolly Roger Bay, there is a star called through the jet streams. I want to get a 100% on the level without getting the metal cap, and I know there is a way to swim and grab it. Has that been disabled in 3D All-Stars for the Switch? If not, will someone tell me where to swim?
The SM64 version in all stars is not exactly the one you played as a kid. Its one released later in japan that took into consideration the rumble pack. https://www.nintendolife.com/news/2020/09/feature_whats_the_deal_with_super_mario_64s_shindou_pak_taiou_version_anyway
It fixes a big glitch (the backwards long jump) but doesn't mention fixes to swimming and all that. The only thing I can see that would impact what you are saying is that 'some levels had slight design alterations and more.'
So I guess, if you are used to do it without the metal cap, there could have been one of those 'level design alterations' that are screwing you over. What I know is that that star was made where you were obligated to get the metal cap for the star, and so now its fixed that you cant force it without the cap.
Apparently, it is possible, but youtube comments generally agree that the All-Stars version makes it harder. Video proof:
The tactic appears to be swimming diagonally towards the star and hitting the "stroke" button when, only when, and exactly when Mario's stroke ends. One comment says the commenter used an online metronome to have his button presses be exactly 89 beats per minute to accomplish the task.