I found this Downwarp while just playing casually. I was playing on the Switch VC, but found footage of someone performing it on an N64, posted below. I've been able to easily recreate it 3 times after I found it. I'm not a speedrunner so I don't know if this is new or not, or if it's even useful.

Could be useful for 120, potentially.

just seems like you swam into an invisible wall (which are really ceilings) and since swimming into a ceiling pushes you downward to be below the ceiling, it pushed warped you below the ship

Yeah that's what I think happened as well. I don't think it's a very precise trick, I was able to trigger it about 3 times in the span of about 6 tries, so it's not hard to do. Probably not too useful for runs but if you get it it could save a couple seconds of just swimming. Is there already a faster way to get to the bottom of the bay or no?

i don't think there's any faster method, but this one would only work so long as the ship is still sunken, which is only the case for the first mission, and i don't think that downwarp would save any time for that mission

hyper-necro post but this has probably been known since the game came out and doesnt really have any uses other than something funny that happens to new runners xD